DTC

Description

Possible Causes

Diagnostic Aides

P0102 - Mass Air Flow (MAF) Circuit Low Input

The MAF sensor circuit is monitored by the PCM for low air flow (or voltage) input through the comprehensive component monitor (CCM). If during key ON engine running the air flow (or voltage) changes below a minimum calibrated limit, the test fails.

• MAF sensor disconnected
• MAF circuit open to PCM
• VPWR open to MAF sensor
• PWR GND open to MAF sensor
• MAF RTN circuit open to PCM
• MAF circuit shorted to GND
• Intake air leak (near MAF sensor)
• A closed throttle indication [throttle position (TP) sensor system]
• Damaged MAF sensor
• Damaged PCM

A MAF V PID (MAF PID) reading less than 0.23 volts in continuous memory or key ON and engine running indicates a hard fault.

P0103 - Mass Air Flow (MAF) Circuit High Input

The MAF sensor circuit is monitored by the PCM for high air flow (or voltage) input through the comprehensive component monitor (CCM). If during key ON engine OFF or key ON engine running the air flow (or voltage) changes above a maximum calibrated limit, the test fails.

• MAF sensor screen is blocked
• MAF circuit shorted to VPWR
• Damaged MAF sensor
• Damaged PCM

A MAF V PID (MAF PID) reading less than 4.6 volts in continuous memory or key ON and engine running indicates a hard fault.

P0106 - Barometric (BARO) Pressure Sensor Circuit Performance

Baro sensor input to the PCM is monitored and is not within the calibrated value.

• Slow responding BARO sensor
• Electrical circuit failure
• Damaged BARO sensor
• Damaged PCM

• VREF voltage should be between 4.0 and 6.0 volts

• PID reading is in frequency

P0107 - BARO/MAP Sensor Low Voltage Detected

Sensor operating voltage is less than 0.25 volts (VREF), as a result it failed below the minimum allowable calibrated parameter.

• Open in the circuit, or short to ground
• VREF circuit open, or short to ground
• Damaged BARO/MAP sensor
• Damaged PCM

• VREF should be greater than 4.0 volts

• PID reading is in frequency/volts

P0108 - BARO/MAP Sensor High Voltage Detected

Sensor operating voltage is greater than 5.0 volts (VREF), as a result it failed above maximum allowable calibrated parameter.

• VREF shorted to VWPR
• BARO/MAP signal shorted to VPWR
• Damaged BARO/MAP sensor
• Damaged PCM

VREF should be less than 6.0 volts. PID reading is in frequency/Volts

P0109 - BARO Sensor Circuit Intermittent

The sensor signal to the PCM is failing intermittently.

• Loose electrical connection
• Damaged BARO sensor

Check harness and connection.

P0112 - Intake Air Temperature (IAT) Circuit Low Input

Indicates the sensor signal is less than Self-Test minimum. The IAT sensor minimum is 0.2 volts or 121°C (250°F).

• Grounded circuit in harness
• Damaged sensor
• Improper harness connection
• Damaged PCM

IAT V PID reading less than 0.2 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault.

P0113 - Intake Air Temperature (IAT) Circuit High Input

Indicates the sensor signal is greater than Self-Test maximum. The IAT sensor maximum is 4.6 volts or -50°C (-58°F).

• Open circuit in harness
• Sensor signal short to power
• Damaged sensor
• Improper harness connection
• Damaged PCM

IAT V PID reading greater than 4.6 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault.

P0116 - Engine Coolant Temperature Circuit Range/Performance Failure

Indicates the engine coolant temperature rationality test has failed. The PCM logic that sets this DTC indicates that engine coolant temperature sensor (ECT or CHT) drifted higher than the nominal sensor calibration curve and could prevent one or more OBD monitors from executing.
The PCM runs this logic after an engine off "calibrated soak period (typically 6 hours). This soak period allows the Intake Air Temperature (IAT) and engine coolant temperature (CHTor ECT) to stabilize and not differ by more than a calibrated value. DTC P0116 is set when all of the following conditions are met:

• Engine coolant temperature at engine start exceeds IAT at engine start by more than a calibrated value, typically 30°F (1°C).
• Engine coolant temperature exceeds a calibrated value, typically 225°F (107°C).
• The Fuel, Heated Oxygen Sensor, Catalyst and Misfire monitors have not completed.
• Calibrated timer to set DTC P0116 has expired.

• Engine Coolant Temperature (ECT) or Cylinder Head Temperature (CHT) sensor
• Coolant System Concern

Ensure IAT and engine coolant temperature are similar when engine is cold. Also ensure engine coolant temperature sensor (ECT or CHT) and actual engine operating temperature are the same.

P0117 - Engine Coolant Temperature (ECT) Circuit Low Input

Indicates the sensor signal is less than Self-Test minimum. The ECT sensor minimum is 0.2 volts or 121°C (250°F). Note on some vehicles that are not equipped with an ECT sensor, CHT can be used and can set this DTC.

• Grounded circuit in harness
• Damaged sensor
• Improper harness connection
• Damaged PCM

ECT V PID reading less than 0.2 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault.

P0118 - Engine Coolant Temperature (ECT) Circuit High Input

Indicates the sensor signal is greater than Self-Test maximum. The ECT sensor maximum is 4.6 volts or -50°C (-58°F). Note on some vehicles that are not equipped with an ECT sensor, CHT can be used and can set this DTC.

• Open circuit in harness
• Sensor signal short to power
• Damaged PCM
• Improper harness connection
• Damaged sensor

ECT V PID reading greater than 4.6 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault.

P0121 - Throttle Position (TP) Circuit Performance Problem

The TP sensor circuit is monitored by the PCM for a non closed throttle position at idle. If key ON engine running self-test terminates upon placing the transmission range selector in gear (DRIVE or REVERSE) or when closing the throttle (idle) after opening it (in PARK or NEUTRAL) the TP closed throttle position is not attained, the test fails.

• Binding throttle linkage
• Damaged throttle body
• TP circuit open to PCM
• Damaged TP sensor
• SIG RTN circuit open to TP sensor

Drive vehicle, bring to a stop, turn key OFF. Start vehicle, run key ON engine running self-test at idle. Access KOER diagnostic trouble codes on scan tool.

P0121 - ETC Throttle Position (TP1) sensor Circuit Range/Performance

The ETC TP1 was flagged as fault status by the PCM indicating the an out of range in either the closed or wide open throttle modes.

• Obstruction in throttle linkage
• Damaged throttle body
• TP1 circuit open to PCM
• Damaged TP1 sensor
• SIG RTN circuit open to TP1 sensor

Fault exhibits a symptom of limited power. A TP1 PID (TP V PID) reading less than 13% (.65 volt), or greater than 93% (4.65volts) in key ON engine OFF, continuous memory or key ON engine running indicates a hard fault.

P0122 - Throttle Position (TP) sensor Circuit Low Input

The TP sensor circuit is monitored by the PCM for a low TP rotation angle (or voltage) input through the comprehensive component monitor (CCM). If during key ON engine OFF or key ON engine running the TP rotation angle (or voltage) changes below a minimum calibrated limit, the test fails.

• TP sensor not seated properly
• TP circuit open to PCM
• VREF open to TP sensor
• TP1 circuit short to GND
• Damaged TP sensor
• Damaged PCM

Fault exhibits a symptom of limited power. A TP PID (TP VPID) reading less than 3.42% (0.17 volt) in key ON engine OFF, continuous memory or key ON engine running indicates a hard fault.

P0122 - ETC Throttle Position (TP1) sensor Circuit Low Input

The ETC TP1 sensor was flagged as fault status by the PCM indicating a low voltage, or open circuit.

• Open ETC TP1 sensor harness
• Short to ground in ETC TP1 sensor harness
• Damaged TP1 sensor
• SIG RTN circuit open to TP1 sensor

Fault exhibits a symptom of limited power. A TP1 PID(TP V PID) reading less than 3.42% (0.17 volt) in key ON engine OFF, continuous memory or key ON engine running indicates a hard fault.

P0123 - Throttle Position (TP) Circuit High Input

The TP sensor circuit is monitored by the PCM for a high TP rotation angle (or voltage) input through the comprehensive component monitor (CCM). If during key ON engine OFF or key ON engine running the TP rotation angle (or voltage) changes above maximum calibrated limit, the test fails.

• TP sensor not seated properly
• TP circuit short to PWR
• TP circuit short to ETCREF
• SIG RTN circuit open to TP sensor
• Damaged TP sensor
• Damaged PCM

A TP PID (TP V PID) reading greater than 93% (4.65 volts) in key ON engine OFF, continuous memory or key ON engine running indicates a hard fault.

P0123 - ETC Throttle Position (TP1) sensor Circuit High Input

The ETC TP sensor 1 was flagged as fault status by the PCM indicating high voltage.

• ETC TP1 sensor harness shorted to VREF
• ETC TP1 sensor harness shorted to PWR
• Damaged TP1 sensor
• VREF circuit shorted to TP1 sensor

Drive vehicle, bring to a stop, turn key OFF. Start vehicle, run key ON engine running self-test at idle. Access KOER diagnostic trouble codes on scan tool.

P0125 - Insufficient Coolant Temperature For Closed Loop Fuel Control

Indicates the ECT or CHT sensor has not achieved the required temperature level to enter closed loop operating conditions within a specified amount of time after starting the engine.

• Insufficient warm up time
• Low engine coolant level
• Leaking or stuck open thermostat
• Malfunctioning ECT sensor
• Malfunctioning CHT sensor

Compare thermostat specification to actual engine coolant temperature using the engine temperature PID (ECT or CHT). Temperature reading should be similar when engine is at normal operating temperature.

P0127 - Intake Air Temperature Too High

Indicates that IAT2 sensor has detected a potential abnormality in the intercooler system. This condition will cause the boost from the supercharger to be bypassed to avoid potential engine damage.

• Blockage of heat exchangers
• Low fluid level
• Fluid leakage
• Intercooler pump or relay failure
• Crossed intercooler coolant lines

Monitor IAT2 PID. Typical IAT2 temperature should be greater than IAT1.

P0128 - Coolant Thermostat (Coolant Temp Below Thermostat Regulating Temperature)

Indicates that the Thermostat Monitor has not achieved the required engine operating temperature level within a specified amount of time after starting the engine.

• Insufficient warm up time
• Low engine coolant level
• Leaking or stuck open thermostat
• Malfunctioning ECT sensor
• Malfunctioning CHT sensor

Refer to Thermostat Monitor in Section 1, Description and Operation, for system information.

P0131 - HO2S Sensor Circuit Out of Range Low Voltage (HO2S-11)

The HO2S sensor is monitored for a negative voltage known as characteristic shift downward (CSD). If the sensor is thought to be switching from 0 volts to -1 volts during testing, the PCM will use this input and remain in fuel control.

• Contaminated HO2S (water, fuel, etc)
• Crossed HO2S signal/signal return wiring

P0132 - HO2S Sensor Circuit High Voltage (HO2S-11)

The HO2S Sensor Signals are monitored for an over voltage fault. The code is set when HO2S signal voltage is 1.5 volts or greater.

• HO2S Signal Circuit shorted to Heater Power inside of HO2S sensor.
• HO2S Signal Circuit shorted to VPWR or VREF in harness.
• PCM failure.

An HO2S PID switching across 0.45 volt from 0.2 to 0.9 volts indicates a normal switching HO2S. HO2S PID voltage of 1.5 volts or greater indicates a short to power.

P0133 - HO2S Sensor Circuit Slow Response (HO2S-11)

The HEGO Monitor checks the HO2S Sensor frequency and amplitude. If during testing the frequency and amplitude were to fall below a calibrated limit, the test will fail.

• Contaminated HO2S sensor.
• Exhaust leaks.
• Shorted /open wiring.
• Improper fueling.
• MAF sensor.
• Deteriorating HO2S sensor.
• Inlet air leaks.

Access HO2S test results from the Generic OBD-II menu to verify DTC.

P0135 - HO2S Sensor Circuit Malfunction (HO2S-11)

During testing the HO2S Heaters are checked for opens/shorts and excessive current draw. The test fails when current draw exceeds a calibrated limit and/or an open or short is detected.

• Short to VPWR in harness or HO2S.
• Water in harness connector.
• Open VPWR circuit.
• Open GND circuit.
• Low battery voltage.
• Corrosion or poor mating terminals and wiring
• Damaged HO2S heater.
• Damaged PCM.

• Wiring.
• Damaged HO2S heater.
• Damaged PCM.

P0136 - HO2S Sensor Circuit Malfunction (HO2S-12)

The downstream HO2S sensor(s) are continuously checked for maximum and minimum voltages. The test fails when the voltages fail to meet the calibrated limits.

• Pinched, shorted, and corroded wiring and pins.
• Crossed sensor wires.
• Exhaust leaks.
• Contaminated or damaged sensor.

P0138 - HO2S Sensor Circuit High Voltage (HO2S-12)

See DTC P0132.

• See possible causes for P0132.

See diagnostic aids for P0132.

P0141 - HO2S Sensor Circuit Malfunction (HO2S-12)

See DTC P0135

P0148 - Fuel Delivery Error

At least one bank lean at wide open throttle.

• Severely restricted fuel filter.
• Severely restricted fuel supply line.

P0151 - HO2S Sensor Circuit Out of Range Low Voltage (HO2S-21)

See DTC P0131

P0152 - HO2S Sensor Circuit High Voltage (HO2S-21)

See DTC P0132.

• See possible causes for P0132.

See diagnostic aids for P0132.

P0153 - HO2S Sensor Circuit Slow Response (HO2S-21)

See DTC P0133

P0155 - HO2S Sensor Circuit Malfunction (HO2S-21)

See DTC P0135

P0156 - HO2S Sensor Circuit Malfunction (HO2S-22)

See DTC P0136

P0158 - HO2S Sensor Circuit High Voltage (HO2S-22)

See DTC P0132.

• See possible causes for P0132.

See diagnostic aids for P0132.

P0161 - HO2S Sensor Circuit Malfunction (HO2S-22)

See DTC P0135

P0171 - System to Lean (Bank 1)

The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit.

Air Measurement System

• MAF sensor (contaminated, damaged, malfunctioning, etc.)

Fuel System

• Fuel pressure regulator (leaking, malfunctioning, etc.).
• Fuel filter plugged, dirty.
• Fuel pump (weak, check valve leaking, etc.).
• Leaking/contaminated fuel injectors.
• Low fuel pressure or running out of fuel.
• EVAP canister purge valve leaking (when canister is "clean").
• Fuel supply line restricted.
• Fuel rail pressure sensor (incorrect reading).

Air Induction System

• Air leaks after the MAF.
• Vacuum Leaks.
• PCV system (leak, valve stuck open, etc.)
• Improperly seated engine oil dipstick.

Exhaust System

• Exhaust leaks before or near the HO2Ss (exhaust manifold gasket, mating gaskets, etc.)..

EGR System

• EGR valve tube/gasket leak
• EVR solenoid vacuum leak

Secondary Air Injection

• Damaged/malfunctioning secondary air injection system (mechanically stuck valve).

View Freeze Frame Data to determine operating conditions when DTC was set. Observe LONGFT1 and 2 PID(s).

P0172 - System to Rich (Bank 1)

The Adaptive Fuel Strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a lean calibrated limit.

Air Measurement System

• MAF sensor (contaminated, damaged, corroded connector, etc.).

Fuel System

• Fuel pressure regulator (vacuum hose off, diaphram leak, malfunctioning, etc.).
• Leaking fuel injectors.
• Fuel return line restricted.
• Fuel rail pressure sensor (incorrect reading).
• EVAP canister purge valve leak (when canister is full).

Base engine

• Engine oil contamination.

View Freeze Frame Data to determine operating conditions when DTC was set. Observe LONGFT1 and 2 PID(s).

P0174 - System to Lean (Bank 2)

The Adaptive Fuel Strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit.

See Possible Causes for P0171.

See Diagnostic Aides for P0171

P0175 - System to Rich (Bank 2)

The Adaptive Fuel Strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a lean calibrated limit.

See Possible Causes for P0172.

See Diagnostic Aides for P0172

P0180 - Engine Fuel Temperature Sensor A Circuit Low Input (EFT)

The comprehensive component monitor (CCM) monitors the EFT sensor circuit to the PCM for low and high voltage. If voltage were to fall below or exceed a calibrated limit and amount of time during testing, the test will fail.

• Open or short in harness.
• Low ambient temperature operation.
• Improper harness connection.
• Damaged EFT sensor.
• Damaged PCM.

Verify EFT-PID value to determine open or short.

P0181 - Engine Fuel Temperature Sensor A Circuit Range/ Performance (EFT)

The comprehensive component monitor (CCM) monitors the EFT Temperature for acceptable operating temperature. If during testing voltage were to fall below or exceed a calibrated limit, a calibrated amount of time the test will fail.

• Open or short in harness.
• Low ambient temperature operation.
• Improper harness connection.
• Damaged EFT sensor.
• Damaged PCM.

Verify EFT-PID value to determine open or short.

P0182 - Engine Fuel Temperature Sensor A Circuit Low Input (EFT)

The comprehensive component monitor (CCM) monitors the EFT sensor circuit to the PCM for low voltage. If voltage were to fall below a calibrated limit and amount of time during testing, the test will fail.

• Short in harness.
• VREF open or shorted.
• Low ambient temperature operation.
• Improper harness connection.
• Damaged EFT sensor.
• Damaged PCM.

Verify EFT-PID and VREF values to determine open or short.

P0183 - Engine Fuel Temperature Sensor A Circuit High Input (EFT)

The comprehensive component monitor (CCM) monitors the EFT sensor circuit to the PCM for high voltage. If voltage were to exceed a calibrated limit and a calibrated amount of time during testing, the test will fail.

• Open or short to PWR in harness.
• Damaged EFT sensor.
• Improper harness connection.
• Damaged PCM.

Verify EFT-PID value to determine open or short.

P0186 - Engine Fuel Temperature Sensor B Circuit Range/Performance (EFT)

See DTC P0181

P0187 - Engine Fuel Temperature Sensor B Circuit Low Input (EFT).

See DTC P0182

P0188 - Engine Fuel Temperature Sensor B Circuit High Input (EFT)

See DTC P0183

P0190 - Fuel Rail Pressure Sensor Circuit Malfunction (FRP)

The comprehensive component monitor (CCM) monitors the FRP sensor to the PCM for VREF voltage. The test fails when the VREF voltage from the PCM drops to a voltage less than a minimum calibrated value.

• VREF open in harness.
• VREF open in sensor.
• VREF open in PCM.

Verify VREF voltage between 4.0 and 6.0V.

P0191 - Fuel Rail Pressure Sensor Circuit Performance (FRP)

The comprehensive component monitor (CCM) monitors the FRP pressure for acceptable fuel pressure. The test fails when the fuel pressure falls below or exceeds a minimum/maximum calibrated value for a calibrated period of time.

• High fuel pressure.
• Low fuel pressure.
• Damaged FRP sensor.
• Excessive resistance in circuit.
• Low or no fuel.

A FRP PID value during KOER of 138 kpa (20 psi) and 413 kpa (60 psi) for gasoline or 586 kpa (85 psi) and 725 kpa (105 psi) for natural gas vehicles (NG) is acceptable.

P0192 - Fuel Rail Pressure Sensor Circuit Low Input (FRP)

The comprehensive component monitor (CCM) monitors the FRP sensor circuit to the PCM for low voltage. If voltage were to fall below a calibrated limit and amount of time during testing, the test will fail.

• FRP signal shorted to SIG RTN or PWR GND.
• FRP signal open (NG only)
• Low fuel pressure (NG only)
• Damaged FRP sensor.
• Damaged PCM.

A FRP PID value during KOER or KOEO less than 0.3 volts for gasoline or 0.5 volts for natural gas vehicles (NG) would indicate a hard fault.

P0193 - Fuel Rail Pressure Sensor Circuit High Input (FRP)

The comprehensive component monitor (CCM) monitors the FRP sensor circuit to the PCM for high voltage. If voltage were to fall below a calibrated limit and a calibrated amount of time during testing, the test will fail.

• FRP signal shorted to VREF or VPWR.
• FRP signal open (gasoline only)
• Low fuel pressure (NG only)
• Damaged FRP sensor.
• Damaged PCM.
• High fuel pressure (caused by damaged fuel pressure regulator) NG.

A FRP PID value during KOER or KOEO less than 0.3 volts for gasoline or 0.5 volts for natural gas vehicles (NG) would indicate a hard fault.

P0196 - Engine Oil Temperature (EOT) Sensor Circuit Range/Performance

Indicates that the sensed EOT value from the EOT sensor is not within the PCM predicted engine oil temperature range, based on other PCM inputs.

• Engine not at operating temperature
• Cooling system problem of stuck thermostat
• EOT circuit failure
• Damaged PCM

EOT rationality test looks for the engine oil temperature sensor to be within a calibrated delta of the PCM predicted engine oil temperature. Ensure EOT sensor reading is similar to engine temperature. If EOT reading greatly differs from engine temperature. Check EOT circuitry for correct operation.

P0197 - Engine Oil Temperature (EOT) Sensor Circuit Low Input

Indicates EOT signal voltage is low (high temperature)

• Damaged harness
• Damaged sensor
• Damaged harness connector
• Damaged PCM

EOT V PID reading less than 0.2 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault short to ground.

P0198 - Engine Oil Temperature (EOT) Sensor Circuit High Input

Indicates EOT signal voltage is high (low temperature)

• Damaged harness
• Damaged sensor
• Damaged harness connector
• Damaged PCM

EOT V PID reading greater than 4.5 volts with key ON and engine OFF or during any engine operating mode indicates an open circuit hard fault.

P0201 through P0212 - Cylinder #1 through Cylinder #12 Injector Circuits

The comprehensive component monitor (CCM) monitors the operation of the fuel injector drivers in the PCM. The test fails when the fuel injector does not operate electrically even though the harness assembly and fuel injectors test satisfactorily.

• Faulty fuel injector driver within the PCM.

PID Data Monitor INJ1F-INJ12F fault flags = YES.

P0217 - Engine Coolant Over-Temperature Condition

Indicates an engine overheat condition was detected by the engine temperature sensor (CHT or ECT depending how vehicle is equip). This condition will cause the boost from the supercharger to be bypassed to avoid potential engine damage.

• Engine cooling system concerns.
• Low engine coolant level.
• Base engine concerns.

Monitor engine temperature PID (CHT or ECT) for overheat condition. Typical engine temperature should be close to cooling system thermostat specification.

P0219 - Engine Over Speed Condition

Indicates the vehicle has been operated in a manner, which caused the engine speed to exceed a calibration limit. The engine rpm is continuously monitored and evaluated by the PCM. The DTC is set when the rpm exceeds the calibrated limit set within the PCM.

• Wheel slippage (water, ice, mud and snow)
• Excessive engine rpm in NEUTRAL or operated in the wrong transmission gear

The DTC indicates the vehicle has been operated in a manner, which caused the engine speed to exceed a calibrated limit.

P0221 - Throttle Position (TP2) sensor Circuit Range/Performance

The ETC TP sensor 2 was flagged as fault status the PCM indicating the an out of range in either the closed or wide open throttle modes.

• Obstructed throttle linkage
• Damaged throttle body
• TP circuit open to PCM
• Damaged TP2 sensor
• SIG RTN circuit open to TP2 sensor
• Self test operator error (foot resting on the accelerator pedal during test)

Fault exhibits a symptom of limited power. A TP2 PID (TP V PID) reading greater than 96.42% (4.65 volts) in key ON engine OFF, continuous memory or key ON engine running indicates a hard fault.

P0222 - Throttle Position (TP2) sensor Circuit Low Input

The ETC TP sensor 2 was flagged as fault status by the PCM indicating a low voltage, or open circuit.

• Open ETC TP2 sensor harness
• Short to ground in ETC TP2 sensor harness
• Damaged TP2 sensor
• SIG RTN circuit open to TP2 sensor

Fault exhibits a symptom of limited power. A TP2 PID (TP V PID) reading less than 3.42% (.17 volts) in key ON engine OFF, continuous memory or key ON engine running indicates a hard fault.

P0223 - Throttle Position (TP2) sensor Circuit High Input

The ETC TP2 sensor was flagged as fault status by the PCM indicating a high voltage.

• ETC TP2 sensor harness shorted to VREF
• Damaged TP2 sensor
• ETC TP2 circuit open
• VREF circuit shorted to TP2 sensor

Fault exhibits a symptom of limited power. A TP2 PID (TP V PID) reading greater than 93% (4.65 volts) in key ON engine OFF, continuous memory or key ON engine running indicates a hard fault.

P0230 - Fuel Pump Primary Circuit Malfunction

NOTE: For natural gas applications, the following description applies to the fuel shutoff valve (FSV) circuit.
The PCM monitors the fuel pump (FP) circuit output from the PCM. The test fails if: With the FP output commanded ON (grounded), excessive current draw is detected on the FP circuit; or with the FP output commanded OFF, voltage is not detected on the FP circuit (the PCM expects to detect VPWR voltage coming through the fuel pump relay coil to the FP circuit).

• Open or shorted fuel pump (FP) circuit
• Open VPWR circuit to fuel pump relay
• Damaged fuel pump relay
• Damaged PCM

• When the FPF PID reads YES, a fault is currently present.
• An open circuit or short to ground can only be detected with the fuel pump commanded OFF.
• A short to power can only be detected with the fuel pump commanded ON.
• During KOEO and KOER self-test, the fuel pump output command will be cycled ON and OFF.

P0231 - Fuel Pump Secondary Circuit Low

NOTE: For natural gas applications, the following description applies to the fuel shutoff valve monitor (FSVM) and the fuel shutoff valve power (FSV PWR) circuits.
The PCM monitors the fuel pump monitor (FPM) circuit. The test fails if the PCM commands the fuel pump ON and B+ voltage is not detected on the FPM circuit.

• Open B+ circuit to the fuel pump relay
• Open FP PWR circuit between the fuel pump relay and its connection to the FPM circuit
• Damaged fuel pump relay
• Damaged PCM (engine will start)
• For 5.4L SC Lightning, damaged IFS switch, IFS switch relay, or concern with related circuits.

During KOEO self-test, the PCM will command the fuel pump ON so this test can be performed.

P0232 - Fuel Pump Secondary Circuit High

• NOTE: For natural gas applications, the following description applies to the fuel shutoff valve monitor (FSVM) and the fuel shutoff valve power (FSV PWR) circuits.
• The PCM monitors the fuel pump monitor (FPM) circuit. This test fails when the PCM detects voltage on the FPM circuit while the fuel pump is commanded OFF. The FPM circuit is wired to a pull-up voltage inside the PCM. The FPM circuit will go high if, with the key ON and the fuel pump commanded OFF, the FPM/FP PWR circuit loses its path to ground through the fuel pump. The FPM circuit will also go high if the FPM/FP PWR circuit is shorted to power.

• Inertia fuel shutoff (IFS) switch not reset or electrically open
• Open circuit between the fuel pump and the FPM connection to the FP PWR circuit
• Poor fuel pump ground
• Fuel pump electrically open
• Fuel pump secondary circuits short to power
• Fuel pump relay contacts always closed
• Open FPM circuit between PCM and connection to FP PWR circuit
• Damaged low speed fuel pump relay or concern with related circuits (if equipped).
• Damaged PCM

Continuous memory P0232 can be set if the IFS switch was tripped, then reset, or if the fuel pump circuit is activated when the PCM expected the circuit to be off (i.e. fuel system test or prime procedure).

P0234 - Supercharger Overboost Condition

The PCM disables (bypasses) the supercharger boost and sets a diagnostic trouble code (DTC) to keep from damaging the powertrain (engine or transmission) during potential harmful operating conditions.

• Brake torque (brake on and throttle at wide open)
• Transmission oil temperature (TOT) exceeds calibrated threshold
• Engine over temperature
• Ignition misfire exceeds calibrated threshold
• Knock sensor (KS) failure or knock detected
• Low speed fuel pump relay not switching

Check for other diagnostic trouble codes accompanying the P0234 or check appropriate and available PIDs related to above possible causes.

P0243 - Supercharger (Boost) Bypass Solenoid Circuit Malfunction

The PCM monitors the supercharger (boost) bypass (SCB) solenoid circuit for an electrical failure. The test fails when the signal moves outside the minimum or maximum allowable calibrated parameters for a specified SCB solenoid duty cycle (100% or 0%) by PCM command.

• VPWR circuit open to SCB solenoid
• SCB solenoid circuit shorted to PWR GND or CHASSIS GND
• Damaged SCB solenoid
• SCB solenoid circuit open
• SCB solenoid circuit shorted to VPWR
• Damaged PCM

Disconnect SCB solenoid. Connect test lamp to SCB solenoid harness connector. Cycle SCB driver in PCM by Output Test Mode. Test lamp cycle on and off - SCB solenoid is suspect. Test lamp always on - SCB signal short in harness or PCM. Test always off - SCB signal or VPWR open in harness or PCM.

P0297 - Vehicle Over Speed Condition

Indicates the vehicle has been operated in a manner, which caused the vehicle speed to exceed a calibration limit. The vehicle speed is continuously monitored and evaluated by the PCM. The DTC is set when the vehicle speed exceed the calibrated limit set within the PCM.

• Vehicle driven at a high rate of speed

The DTC indicates the vehicle has been operated in a manner, which caused the engine speed to exceed a calibrated limit.

P0298 - Engine Oil Over Temperature Condition

Indicates the Engine Oil Temperature Protection strategy in the PCM has been activated. This will temporarily prohibit high engine speed operation by disabling injectors, therefore reducing the risk of engine damage from high engine oil temperature. Note: On engines which are equipped with an oil temperature sensor, the PCM reads oil temperature to determine if it is excessive. When an oil temperature sensor is not present, the PCM uses an oil algorithm to infer actual temperature. Engine shutdown strategy function is the same on vehicles with and without oil temperature sensors.

• Very high engine rpm for extended period of time.
• Over-heating condition.
• Malfunction EOT sensor or circuit (vehicles w/EOT sensor).
• Base engine concerns.

Engine operating in high rpm range, due to improper gear selection. May cause Lack/Loss of Power or Surge customer concern.

P0300 - Random Misfire

The random misfire DTC indicates multiple cylinders are misfiring or the PCM cannot identify which cylinder is misfiring.

• Camshaft position sensor (CMP)
• Low fuel: less than 1/8 tank
• Stuck open EGR valve
• Blocked EGR passages

One or more EGR passages may be blocked or partially blocked. If this is the case the Misfire Detection Monitor will indicate the EGR port to check for possible blockage.

P0301 through P0310 - Misfire Detection Monitor

The misfire detection monitor is designed to monitor engine misfire and identify the specific cylinder in which the misfire has occurred. Misfire is defined as lack of combustion in a cylinder due to absence of spark, poor fuel metering, poor compression, or any other cause.

• Ignition system
• Fuel injectors
• Running out of fuel
• EVAP canister purge valve
• Fuel pressure
• Evaporative emission system
• Base engine

The MIL will blink once per second when a misfire is detected severe enough to cause catalyst damage. If the MIL is on steady state, due to a misfire, this will indicate the threshold for emissions was exceeded and cause the vehicle to fail an inspection and maintenance tailpipe test.

P0315 - PCM is unable to learn Crankshaft Pulse Wheel tooth spacing (exceeded the allowable correction tolerances).

PCM is unable to learn and correct for mechanical inaccuracies in Crankshaft Pulse Wheel tooth spacing. This DTC will disable the Misfire Monitor.

• Damaged Crankshaft Pulse Wheel teeth.
• Damaged CKP sensor

Visual inspection of the CKP sensor and Crankshaft Pulse Wheel teeth for damage. Learn profile by performing 3 closed throttle decelerations from 60 to 40 MPH and monitor PIDS to verify mature profile. (For NGS monitor MFFPNP PID and for WDS monitor MP_LRN PID)

P0316 - Misfire Occurred in the First 1000 Engine Revolutions

DTC P0316 will be set in addition to any type B misfire DTC which occurs in the first 1000 revolution test interval, following engine start.

• Damaged CKP sensor
• Ignition system
• Fuel Injectors
• Running out of fuel
• Fuel Quality
• Base Engine
• Damaged PCM

Freeze Frame Data and the P03XX DTC will also be stored, indicating in which cylinder the misfire occurred.

P0320 - Ignition Engine Speed Input Circuit Malfunction

The ignition engine speed sensor input signal to PCM is continuously monitored. The test fails when the signal indicates that two successive erratic profile ignition pickup (PIP) pulses have occurred.

• Loose wires/connectors.
• Arcing secondary ignition components (coil, wires and plugs)
• On board transmitter (2-way radio)

The DTC indicates that two successive erratic PIP pulses occurred.

P0325 - Knock Sensor 1 Circuit Malfunction (Bank 1)

See DTC P0326

P0326 - Knock Sensor 1 Circuit Range/ Performance (Bank 1)

The knock sensor detects vibrations upon increase and decrease in engine rpm. The knock sensor generates a voltage based on this vibration. Should this voltage go outside a calibrated level a DTC will set.

• Knock sensor circuit short to GND
• Knock sensor circuit short to PWR
• Knock sensor circuit open
• Damaged knock sensor
• Damaged PCM

A knock sensor voltage greater than 0.5V with the key ON and engine OFF indicates a hard fault.

P0330 - Knock Sensor 2 Circuit Malfunction (Bank 2)

See DTC P0331

P0331 - Knock Sensor 2 Circuit Range/Performance (Bank 2)

The knock sensor detects vibration upon increase and decrease in engine rpm. The knock sensor generates a voltage based on this vibration. Should this voltage go outside a calibrated level a DTC will set.

• Knock sensor circuit short to GND
• Knock sensor circuit short to PWR
• Damaged knock sensor
• Damaged PCM
• Knock sensor circuit open

A knock sensor voltage greater than 0.5V with the key ON and engine OFF indicates a hard fault.

P0340 - Camshaft Position (CMP) Sensor Circuit Malfunction (Bank 1)

The test fails when the PCM can no longer detect the signal from the CMP sensor on Bank 1.

• CMP circuit open
• CMP circuit short to GND
• CMP circuit short to PWR
• SIG RTN open (VR sensor)
• CMP GND open (Hall effect sensor)
• CMP misinstalled (Hall effect sensor)
• Damaged CMP sensor shielding
• Damaged CMP sensor
• Damaged PCM

Harness routing, harness alterations, improper shielding, or electrical interference from other improperly functioning systems may have intermittent impact on the CMP signal.

P0345 - Camshaft Position (CMP) Sensor Circuit Malfunction (Bank 2)

The test fails when the PCM can no longer detect the signal from the CMP sensor on Bank 2.

• CMP circuit open
• CMP circuit short to GND
• CMP circuit short to PWR
• SIG RTN open (VR sensor)
• CMP GND open (Hall effect sensor)
• CMP misinstalled (Hall effect sensor)
• Damaged CMP sensor shielding
• Damaged CMP sensor
• Damaged PCM

Harness routing, harness alterations, improper shielding, or electrical interference from other improperly functioning systems may have intermittent impact on the CMP signal.

P0350 - Ignition Coil (Undetermined) Primary/ Secondary Circuit Malfunction

Each ignition primary circuit is continuously monitored. The test fails when the PCM does not receive a valid IDM pulse signal from the ignition module (integrated in PCM).

• Open or short in Ignition START/RUN circuit
• Open coil driver circuit
• Coil driver circuit shorted to ground
• Damaged coil
• Damaged PCM
• Coil driver circuit shorted to VPWR

P0351 Through P0360 - Ignition Coil A through J Primary/Secondary Circuit Malfunction

Each ignition primary circuit is continuously monitored. The test fails when the PCM does not receive a valid IDM pulse signal from the ignition module (integrated in PCM).

• Open or short in Ignition START/RUN circuit
• Open coil driver circuit in harness
• Coil driver circuit shorted to ground
• Damaged coil
• Damaged PCM
• Coil driver circuit shorted to PWR

P0400 EGR Flow Failure (outside the minimum or maximum limits)

The EEGR system is monitored once per drive cycle during steady state conditions above 48 mph . The test will fail when a malfunction is detected by PCM calculations indicating the EGR flow is less or greater than expected.

• EEGR valve stuck open or closed
• Connector to EEGR not seated
• EEGR motor windings shorted or open circuited
• No power to EEGR
• Harness open or shorted to power or ground
• Vacuum signal to MAP restricted or leaking
• MAF sensor signal erroneous
• Damaged PCM
• Carbon build up in EEGR valve seat area
• One or more sensor not responding or out of range

All of the following sensors input data to the PCM for proper operation of the EEGR system: ECT, CPS, IAT, MAF, TP, MAP. Any DTC relating to these sensors must be resolved prior to addressing P0400 code.

P0401 - EGR Flow Insufficient Detected

The EGR system is monitored during steady state driving conditions while the EGR is commanded on. The test fails when the signal from the DPF EGR sensor indicates that EGR flow is less than the desired minimum.

• Vacuum supply
• EGR valve stuck closed
• EGR valve leaks vacuum
• EGR flow path restricted
• EGRVR circuit shorted to PWR
• VREF open to D.P.F. EGR sensor
• D.P.F. EGR sensor downstream hose off or plugged
• EGRVR circuit open to PCM
• VPWR open to EGRVR solenoid
• D.P.F. EGR sensor hoses both off
• D.P.F. EGR sensor hoses reversed
• Damaged EGR orifice tube
• Damaged EGRVR solenoid
• Damaged PCM

Perform KOER self-test and look for P1408 as an indication of a hard fault. If P1408 is not present, look for contamination, restrictions, leaks, and intermittents.

P0402 - EGR Flow Excessive Detected

The EGR system is monitored for undesired EGR flow during idle. The EGR monitor looks at the DPF EGR signal at idle and compares it to the stored signal measured during key ON and engine OFF. The test fails when the signal at idle is greater than at key ON engine OFF by a calibrated amount.

• EGR valve stuck open
• Plugged EGR vacuum regulator solenoid vent
• Plugged EGR tube
• Slow responding D.P.F. EGR sensor
• Damaged DPF EGR sensor
• Improper vacuum hose connection
• Plugged vacuum hoses
• EGRVR circuit shorted to ground
• Damaged EGR vacuum regulator solenoid
• Damaged PCM

A DPFEGR PID reading that is greater at idle than during key ON and engine OFF by 0.5 volt or a rough engine idle, may indicate a hard fault.

P0403 EEGR Electric Motor Windings Or Circuits To The PCM Shorted Or Open (Vehicles with Electric EGR)

The EEGR system is continously monitored to check the 4 EEGR motor coils, circuits, and the PCM for opens, shorts to power and ground. If a malfunction is detected the EEGR system will be disabled and additional monitoring will be suspended for the remainder of the drive until the next drive cycle.

• EEGR motor windings open
• Connector to EEGR not seated
• Open circuit in harness from PCM to EEGR
• Open circuit in PCM
• Short circuit in EEGR motor
• Short circuit in harness from PCM to EEGR
• Short circuit in PCM

If an intermittent condition is suspected the most effective methoid of wiring fault isolation is to use the wiggle test methoid while measuring for shorts and open circuits.

P0403 - EGR Vacuum Regulator Solenoid Circuit Malfunction (Vehicles with out Electric EGR)

This test checks the electrical function of the EGRVR solenoid. The test fails when the EGRVR circuit voltage is either too high or too low when compared to the expected voltage range. The EGR system must be enabled for the test to be completed.

• EGRVR circuit open
• VPWR open to EGRVR solenoid
• EGRVR circuit short to VPWR or GND
• Damaged EGRVR solenoid
• Damaged PCM

The EGR vacuum regulator solenoid resistance is from 26 to 40 ohms.

P0405 - DPF EGR Sensor Circuit Low Voltage Detected

See DTC P1400

P0406 - DPF EGR Sensor Circuit High Voltage Detected

See DTC P1401

P0411 - Secondary Air Injection (AIR) system upstream flow

See DTC P1411

P0412 - Secondary Air Injection System (AIR) circuit malfunction

The PCM attempts to control when air is injected in the exhaust. The DTC indicates a Secondary Air injection system AIR circuit fault.

• AIR circuit open
• AIR bypass solenoid fault
• Damaged PCM
• AIR circuit short to power
• Solid state relay fault
• Damaged AIR pump

The AIR circuit is normally held high through the AIR bypass solenoid and SSR when the output driver is off. Therefore, a low AIR circuit indicates a driver is always on and a high circuit indicates an open in the PCM.

P0420 - Catalyst System Efficiency Below Threshold (Bank 1)

Indicates Bank 1 catalyst system efficiency is below the acceptable threshold

• Use of leaded fuel
• Damaged HO2S
• Malfunctioning ECT
• High fuel pressure
• Damaged exhaust manifold
• Damaged catalytic converter
• Oil contamination
• Cylinder misfiring
• Downstream HO2S wires improperly connected
• Damaged exhaust system pipe
• Damaged muffler/tailpipe assembly
• Retarded spark timing

Compare HO2S upstream and downstream switch rate and amplitude. Under normal closed loop fuel conditions, high efficiency catalysts have oxygen storage which makes the switching frequency of the downstream HO2S very slow and reduces the amplitude of those switches as compared to the upstream HO2S. As catalyst efficiency deteriorates, its ability to store oxygen declines and the downstream HO2S signal begins to switch more rapidly with increase amplitude, approaching the switching rate and amplitude of the upstream HO2S. Once beyond an acceptable limit the DTC is set.

P0430 - Catalyst System Efficiency Below Threshold (Bank 2)

Indicates Bank 2 catalyst system efficiency is below the acceptable threshold.

• Use of leaded fuel
• Damaged HO2S
• Malfunctioning ECT
• High fuel pressure
• Damaged exhaust manifold
• Damaged catalytic converter
• Oil contamination
• Cylinder misfiring
• Downstream HO2S wires improperly connected
• Damaged exhaust system pipe
• Damaged muffler/tailpipe assembly
• Retarded spark timing

Compare HO2S upstream and downstream switch rate and amplitude. Under normal closed loop fuel conditions, high efficiency catalysts have oxygen storage which makes the switching frequency of the downstream HO2S very slow and reduces the amplitude of those switches as compared to the upstream HO2S. As catalyst efficiency deteriorates, its ability to store oxygen declines and the downstream HO2S signal begins to switch more rapidly with increase amplitude, approaching the switching rate and amplitude of the upstream HO2S. Once beyond an acceptable limit the DTC is set.

P0442 - EVAP Control System Leak Detected (Small Leak)

The PCM monitors the complete EVAP control system for presence of a small fuel vapor leak. The system failure occurs when a fuel vapor leak from an opening as small as 1.016 mm (0.04 inch) is detected by the EVAP running loss monitor test.

• After-market EVAP hardware (such as fuel filler cap) non-conforming to required specifications
• Small holes or cuts in fuel vapor hoses/tubes
• Canister vent solenoid stays partially open on closed command
• Damaged, cross-threaded or loosely installed fuel filler cap
• Loose fuel vapor hose/tube connections to EVAP system components
• EVAP system component seals leaking (EVAP canister purge valve, fuel tank pressure sensor, canister vent solenoid, fuel vapor control valve tube assembly or fuel vapor vent valve assembly)

P0443 - EVAP Control System Canister Purge Valve Circuit Malfunction

The PCM monitors the state of the EVAP canister purge valve circuit output driver. The test fails when the signal moves outside the minimum or maximum limit for the commanded state.

• VPWR circuit open
• EVAP canister purge valve circuit shorted to GND
• Damaged EVAP canister purge valve
• EVAP canister purge valve circuit open
• EVAP canister purge valve circuit shorted to VPWR
• Damaged PCM

To verify normal function, monitor the EVAP canister purge valve signal PID EVAPPDC (or EVMV for electronic valve) and the signal voltage (PCM control side). With the valve closed, EVAPPDC will indicate 0 percent duty cycle (0 mA for EVMV) and the voltage approximately equal to battery voltage. When the valve is commanded fully open, EVAPPDC will indicate 100 percent duty cycle (1000mA for EVMV) and a voltage drop of 3 volts minimum is normal. Output test mode may be used to switch output ON/OFF to verify function.

P0446 - EVAP Control System Canister Vent Solenoid Circuit Malfunction

Monitors the canister vent (CV) solenoid circuit for an electrical failure. The test fails when the signal moves outside the minimum or maximum allowable calibrated parameters for a specified canister vent duty cycle by PCM command.

• VPWR circuit open
• CV solenoid circuit shorted to PWR GND or CHASSIS GND
• Damaged CV solenoid
• CV solenoid circuit open
• CV solenoid circuit shorted to VPWR
• Damaged PCM

• Monitor EVAPCV PID and voltage between canister vent solenoid signal and PWR GND in output test mode with key ON engine OFF (or in key ON engine RUNNING mode)
• EVAPCV PID at 0% and voltage less than 1.0 volt (or EVAPCV PID at 100% and voltage greater than 0.5 volt) indicates a hard fault

P0451 - FTP Sensor Circuit Noisy

The fuel tank pressure changes greater than 14 inches of H ₂ 0 in 0.10 seconds.

• Intermittent open or short in the FTP sensor or the FTP sensor signal.

Monitor FTP PID and does it change from above 15 inches of H ₂ 0 to below a minus (-) 15 inches of H ₂ 0 often in 1.0 minute.

P0452 - FTP Sensor Circuit Low Voltage Detected

The PCM monitors the EVAP control system FTP sensor input signal to the PCM. The test fails when the signal average drops below a minimum allowable calibrated parameter.

• Contamination internal to FTP sensor connector
• Damaged PCM
• FTP circuit shorted to GND or SIG RTN
• Damaged FTP sensor

FTP V PID reading less than 0.22 volt with key ON and engine OFF or during any engine operating mode indicates a hard fault.

P0453 - FTP Sensor Circuit High Voltage Detected

The PCM monitors the EVAP control system FTP sensor input signal to the PCM. The test fails when the signal average jumps above a minimum allowable calibrated parameter.

• FTP circuit open
• VREF shorted to VPWR
• Damaged PCM
• FTP circuit shorted to VREF or VPWR
• SIG RTN circuit open
• Damaged FTP sensor

FTP V PID reading greater than 4.50 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault.

P0455 - EVAP Control System Leak Detected (No Purge Flow or Large Leak)

The PCM monitors the complete EVAP control system for no purge flow, the presence of a large fuel vapor leak or multiple small fuel vapor leaks. The system failure occurs when no purge flow (attributed to fuel vapor blockages or restrictions), a large fuel vapor leak or multiple fuel vapor leaks are detected by the EVAP running loss monitor test with the engine running (but not at idle).

• After-market EVAP hardware (such as fuel filler cap) non-conforming to required specifications
• Disconnected or cracked fuel EVAP canister tube, EVAP canister purge outlet tube or EVAP return tube
• EVAP canister purge valve stuck closed
• Damaged EVAP canister
• Damaged or missing fuel filler cap
• Insufficient fuel filler cap installation
• Loose fuel vapor hose/tube connections to EVAP system components
• Blockages or restrictions in fuel vapor hoses/tubes (items also listed under disconnections or cracks)
• Fuel vapor control valve tube assembly or fuel vapor vent valve assembly blocked
• Canister vent (CV) solenoid stuck open
• Mechanically inoperative fuel tank pressure (FTP) sensor

Check for audible vacuum noise or significant fuel odor in the engine compartment or near the EVAP canister and fuel tank.

P0456 - EVAP Control System Leak Detected (Very Small Leak)

The PCM monitors the complete EVAP control system for the presence of a very small fuel vapor leak. The system failure occurs when a fuel vapor leak from an opening as small as 0.508 mm (0.020 inch) is detected by the EVAP running loss monitor test.

• Very small holes or cuts in fuel vapor hoses/tubes.
• Loose fuel vapor hose/tube connections to EVAP system components.
• EVAP system component seals leaking (refer to Possible Causes under P0442).

P0457 - EVAP Control System Leak Detected (Fuel Filler Cap Loose/Off)

A fuel tank pressure change less than a minus (-) 7 inches of H ₂ 0 in 30 seconds has occurred after refueling; or there is excessive purge (fuel vapor) flow greater than 0.06 pounds per minute.

• Fuel filler cap not installed on refueling (storing continuous memory DTC) and "Check Fuel Cap" light may also be illuminated.
• Fuel filler cap missing, loose or cross-threaded.

Check for missing fuel filler cap or integrity of the cap. If OK, clear continuous memory DTCs and re-initiate EVAP Emission Running Loss Monitor Drive Cycle.

P0460 - Fuel Level Sensor Circuit Malfunction

The PCM monitors the fuel level input (FLI) circuit for electrical failure. The test fails when the signal moves outside the minimum or maximum allowable calibrated parameters for a specified fuel fill percentage in the fuel tank.

• Empty fuel tank
• Fuel pump (FP) module concern
• Incorrectly installed fuel gauge
• Damaged instrument cluster
• CASE GND circuit open
• FLI shorted to VPWR
• Overfilled fuel tank
• Damaged fuel gauge
• FLI circuit open
• FLI circuit shorted to CASE GND or PWR GND
• CSE GND shorted to VPWR
• Damaged PCM

Monitor FLI PID and FLI V PID in key ON engine RUNNING. FLI PID at 25% fill (with non matching fuel gauge) and FLI V PID less than 0.90 volts [for FLI PID at 75% fill (with non matching fuel gauge) and FLI V PID greater than 2.45 volts] indicates a hard fault.

P0462 - Fuel Level Sensor Circuit Low Input

The PCM monitors the fuel level input (FLI) circuit for electrical failure. The test fails when the signal moves below the minimum allowable calibrated parameter for a specified fuel fill percentage in the fuel tank.

• Empty fuel tank
• Fuel pump (FP) module concern
• Incorrectly installed fuel gauge
• Damaged instrument cluster
• Damaged fuel gauge
• FLI circuit open
• FLI circuit shorted to CASE GND or PWR GND
• Damaged PCM

Monitor FLI PID and FLI V PID in key ON engine RUNNING. FLI PID at 25% fill (with non matching fuel gauge) and FLI V PID less than 0.90 volts [for FLI PID at 75% fill (with non matching fuel gauge) and FLI V PID greater than 2.45 volts] indicates a hard fault.

P0463 - Fuel Level Sensor Circuit High Input

The PCM monitors the fuel level input (FLI) circuit for electrical failure. The test fails when the signal moves above the maximum allowable calibrated parameter for a specified fuel fill percentage in the fuel tank.

• Fuel pump (FP) module concern
• Incorrectly installed fuel gauge
• Damaged instrument cluster
• FLI shorted to VPWR
• CASE GND circuit open
• Overfilled fuel tank
• Damaged fuel gauge
• Damaged PCM

Monitor FLI PID and FLI V PID in key ON engine RUNNING. FLI PID at 25% fill (with non matching fuel gauge) and FLI V PID less than 0.90 volts [for FLI PID at 75% fill (with non matching fuel gauge) and FLI V PID greater than 2.45 volts] indicates a hard fault.

P0480 - Low Fan Control (LFC) Primary Circuit Failure
(applications with relay controlled electric cooling fan(s))

Monitors the low fan control (LFC) (fan control [FC] for one speed fan application) primary circuit output from the PCM. The test fails if: When the PCM grounds the LFC/FC circuit, excessive current draw is detected on the LFC/FC circuit; or with the LFC/FC circuit not grounded by the PCM, voltage is not detected on the LFC/FC circuit (the PCM expects to detect VPWR voltage coming through the low speed FC relay [or CCRM] coil to the LFC/FC circuit).

• Open or shorted LFC/FC circuit
• Open VPWR circuit to low speed FC relay
• Damaged low speed FC relay (or CCRM)
• Damaged PCM

• When the LFCF PID reads YES, a fault is currently present
• An open circuit or short to ground can only be detected when the PCM is not grounding the LFC/FC circuit
• A short to power can only be detected when the PCM is grounding the LFC/FC circuit.
• During KOEO and KOER Self-Test, the LFC/FC circuit will be cycled on and off

P0480 - Cooling Fan Electrical Malfunction
(applications with variable speed electric cooling fan)

This test checks the Fan Control - Variable (FCV) output circuit. The DTC sets if the PCM detects that the voltage on the FCV circuit is not within the expected range.

• FCV circuit open or shorted.
• B+ or ground circuit fault to cooling fan.
• VPWR open to cooling fan (if applicable).
• Damaged cooling fan module.
• Damaged PCM.

During KOEO Self-Test, the cooling fan will be cycled on and off.

P0480 - Visctronic Drive Fan (VDF) Primary Circuit Malfunction
(applications with Visctronic Drive cooling fan)

This test checks the electrical function of the (VDF) primary circuit. The DTC sets if the PCM detects voltage too high or too low, when compared to the expected voltage range of the (VDF) primary circuit.

• VDF circuit open.
• VDF circuit short to power.
• VDF circuit short to ground.
• Damaged VDF solenoid.
• Damaged PCM.

The FANVAR_F or VFCF PID will indicate "YES" when there is a VDF circuit fault present.

P0481 - High Fan Control (HFC) Primary Circuit Failure

Monitors the high fan control (HFC) primary circuit output from the PCM. The test fails if: With the HFC output commanded on (grounded), excessive current draw is detected on the HFC circuit; or with the HFC circuit commanded off, voltage is not detected on the HFC circuit (the PCM expects to detect VPWR voltage coming through the high speed FC relay [or CCRM] coil to the HFC circuit).

• Open or shorted HFC circuit
• Open VPWR circuit to high speed FC relay
• Damaged high speed FC relay (or CCRM)
• Damaged PCM

• When the HFCF PID reads YES, a fault is currently present
• An open circuit or short to ground can only be detected when the PCM is not grounding the HFC circuit
• A short to power can only be detected when the PCM is grounding the HFC circuit
• During KOEO and KOER self-test, the HFC circuit will be cycled on and off

P0482 - Medium Fan Control (MFC) Primary Circuit Failure

Monitors the medium fan control (MFC) primary circuit output from the PCM. The test fails if: With the MFC output commanded on (grounded), excessive current draw is detected on the MFC circuit; or with the MFC circuit commanded off, voltage is not detected on the MFC circuit (the PCM expects to detect IGN START/RUN voltage coming through the medium speed FC relay coil to the MFC circuit).

• Open or shorted MFC circuit
• Open IGN START/RUN circuit to medium speed FC relay
• Damaged medium speed FC relay
• Damaged PCM

• Same as P0481, except with MFC circuit and MFCF PID
• Using Output Test Mode on scan tool, when commanding the low speed fan on, the PCM will also activate the medium speed fan output.

P0500 - Vehicle Speed Sensor (VSS) Malfunction

Indicates the powertrain control module (PCM) detected an error in the vehicle speed information. Vehicle speed data is received from either the vehicle speed sensor (VSS), transfer case speed sensor (TCSS) or anti-lock brake system (ABS) control module. If the engine rpm is above the torque converter stall speed (automatic transmission) and engine load is high, it can be inferred that the vehicle must be moving. If there is insufficient vehicle speed data input, a malfunction is indicated and a DTC is set. On most vehicle applications the malfunction indicator lamp (MIL) will be triggered when this DTC is set.

• Open in VSS+/VSS- harness circuit.
• Open in TCSS signal or TCSS signal return harness circuit.
• Short to GND in VSS harness circuit.
• Short to GND in TCSS harness circuit.
• Short to PWR in VSS harness circuit.
• Short to PWR in TCSS harness circuit.
• Open or short in the vehicle speed circuit(s) (VSC) between the PCM and appropriate control module.
• Damaged VSS or TCSS.
• Damaged wheel speed sensors.
• Damaged wheel speed sensor harness circuits.
• Damage in module(s) connected to VSC/VSS circuit.
• Damage drive mechanism for VSS or TCSS.

Monitor VSS PID while driving vehicle. This DTC is set when the PCM detects a sudden loss of vehicle speed signal over a period of time. If vehicle speed data is lost, check the source of where the vehicle speed input originates from: VSS, TCSS or ABS. Note: On some MSOF applications, VSS and TCSS PID can be monitor. However if no TCSS PID is available and VSS PID is zero, TCSS circuitry frequency must be checked for loss of sensor signal. If another vehicle electronic module has generated the P0500 and the vehicle does not receive its vehicle speed input from one of the above mention sources (VSS, TCSS or ABS). Check the PCM for Output Shaft Speed Sensor (OSS) DTCs. On OSS applications the PCM uses the OSS to calculated the vehicle speed. If no OSS DTCs are found check for correct PCM configuration. Check PCM configuration for correct tire size and axle ratio.

P0501 - Vehicle Speed Sensor (VSS) Range/ Performance

Indicates the powertrain control module (PCM) detected an error in the vehicle speed information. This DTC is set the same way as P0500, however the malfunction indicator lamp (MIL) is not triggered.

• Refer to possible causes for P0500.

Refer to diagnostic aids for P0500.

P0503 - Vehicle Speed Sensor (VSS) Intermittent

Indicates poor or noisy VSS performance. Vehicle speed data is received from either the vehicle speed sensor (VSS), transfer case speed sensor (TCSS) or anti-lock brake system (ABS) control module.

• Noisy VSS/TCSS input signal from Radio Frequency Interference/ Electro-Magnetic Interference (RFI/EMI) external sources such as ignition components or charging circuit.
• Damaged VSS or driven gears.
• Damaged TCSS.
• Damaged wiring harness or connectors.
• Malfunction in module(s) or circuit connected to VSS/TCSS circuit.
• After market add-on.

Monitor VSS PID while driving vehicle, check for intermittent vehicle speed indication. Verify ignition and charging system are functioning correctly.

P0505 - Idle Air Control System Malfunction

The PCM attempts to control engine speed during KOER self-test. The test fails when the desired rpm could not be reached or controlled during the self-test.

• IAC circuit open
• VPWR to IAC solenoid open
• IAC circuit shorted to PWR
• Air inlet is plugged
• Damaged IAC valve
• Damaged PCM

The IAC solenoid resistance is from 6 to 13 ohms. Monitor IAC PID duty cycle and/or voltage.

P0506 - Idle Air Control System RPM lower than expected

The PCM attempts to control engine speed during KOER self-test. The test fails when the desired rpm could not be reached or controlled during the self-test.

• IAC circuit shorted to PWR
• VPWR to IAC solenoid open
• IAC circuit open
• Damaged IAC valve
• Damaged PCM
• Air inlet is plugged

The IAC solenoid resistance is from 6 to 13 ohms. Monitor IAC PID duty cycle and/or voltage.

P0507 - Idle Air Control System RPM higher than expected

The PCM attempts to control engine speed during KOER self-test. The test fails when the desired rpm could not be reached or controlled during the self-test.

• IAC circuit shorted to ground
• Damaged IAC valve
• Damaged PCM
• Air intake leak after throttle body

The IAC solenoid resistance is from 6 to 13 ohms. Monitor IAC PID duty cycle and/or voltage.

P0511 - Idle Air Control Circuit Malfunction

The PCM attempts to control engine speed during KOER self-test. The test fails when the desired rpm could not be reached or controlled during the self-test.

• IAC circuit open
• VPWR to IAC solenoid open
• IAC circuit shorted to PWR
• Damaged IAC valve
• Damaged PCM

The IAC solenoid resistance is from 6 to 13 ohms. Monitor IAC PID duty cycle and/or voltage.

P0528 - Visctronic Drive Fan (VDF) Speed Sensor Circuit Malfuntion

During KOER, the PCM cycles the VDF full on (100% duty cycle). If the fan speed input is less than a calibrated value, the DTC is set. When the engine is running, if the fan speed less than the calibrated value, DTC P0528 will be set.

• VDF Speed Sensor circuit open or shorted.
• Vehicle Buffered Power (VBPWR) open or shorted.
• VDF Speed Sensor PWRGND open or shorted.
• Damaged PCM.

The FANSS PID will indicate fan RPM and FANSSM will indicate if the hall sensor for VDF fan speed is always HIGH or LOW.

P0534 - Low A/C Cycling Period

Indicates frequent A/C compressor clutch cycling.

• Mechanical A/C system concern (such as low refrigerant charge, damaged A/C cycling switch)
• Intermittent open between the cycling pressure switch and the PCM
• Intermittent open in IGN RUN circuit to cycling pressure switch (if applicable)

• An intermittent open circuit, although possible, is unlikely
• This test was designed to protect the transmission. In some strategies, the PCM will unlock the torque converter during A/C clutch engagement. If a concern is present that results in frequent A/C clutch cycling, damage could occur if the torque converter was cycled at these intervals. This test will detect this condition, set the DTC and prevent the torque converter from excessive cycling.

P0537 - A/C Evaporator Temperature (ACET) Circuit Low Input

Indicates the ACET signal input is less than Self-Test minimum. Self-Test minimum is 0.13 volts.

• ACET circuit short to ground or SIG RTN
• Damaged ACET sensor
• Damaged PCM

The PCM sources a low current 5 volts on the ACET circuit (this voltage can be measured with the sensor disconnected). As A/C evaporator air temperature changes, the ACET circuit resistance to SIG RTN (ground) changes (which changes the voltage the PCM detects). When the ACET signal is detected below the Self-Test minimum, check for shorts to SIG RTN or ground, which would pull the voltage low.

P0538 - A/C Evaporator Temperature (ACET) Circuit High Input

Indicates the ACET signal input is greater than Self-Test minimum. Self-Test maximum is 4.5 volts.

• ACET circuit open
• SIG RTN circuit open to ACET sensor
• ACET circuit short to power (VREF)
• Damaged ACET sensor
• Damaged PCM

The PCM sources a low current 5 volts on the ACET circuit (this voltage can be measured with the sensor disconnected). As A/C evaporator air temperature changes, the ACET circuit resistance to SIG RTN (ground) changes (which changes the voltage the PCM detects). When the ACET signal is detected above the Self-Test maximum, check for open cirucits (ACET or SIG RTN), which would cause the voltage to remain high. Although not as probable, also check for a short to power (VREF).

P0552 - Power Steering Pressure (PSP) Sensor Circuit Malfunction

The PSP sensor input signal to the PCM is continuously monitored.The test fails when the signal is open or shorted to ground.

• PSP sensor damaged
• SIG RTN circuit open or shorted
• VREF circuit open or shorted
• PSP sensor signal circuit open or shorted
• Damaged PCM

The DTC indicates the PSP sensor circuit is open or shorted to ground.

P0553 - Power Steering Pressure (PSP) Sensor Circuit Malfunction

The PSP sensor input signal to PCM is continuously monitored. The test fails when the signal is shorted to power.

• PSP sensor damaged
• SIG RTN circuit shorted to power
• VREF circuit shorted to power
• PSP sensor signal circuit shorted to power
• Damaged PCM

The code indicates the PSP sensor circuit is shorted to power.

P0597 - Thermostat Heater Control (THTRC) Circuit Failure

The Comprehensive component monitor (CCM) monitors the THTRC circuit to the PCM for high and low voltage. If during testing; voltage was to fall below a calibrated limit for a calibrated amount of time the test will fail and set the DTC and MIL.

• Open or shorted THTRC circuit
• Open VPWR
• Open or shorted thermostat assembly
• Damaged PCM

DTC P0597 is a THTRC circuit check. Testing should include wire harness, thermostat heater and PCM.

P0602 - Control Module Programming Error

This Diagnostic Trouble Code (DTC) indicates programming error within Vehicle ID block (VID).

• VID data corrupted by the scan tool during VID reprogramming

Using the scan tool, reprogram the VID block. If PCM does not allow reprogramming of the VID block, reflashing PCM will be required.

P0603 - Powertrain Control Module KAM Test Error

Indicates the PCM has experienced an internal memory fault. However there are external items that can cause this DTC.

• Reprogramming
• Battery terminal corrosion
• KAPWR to PCM interrupt/open
• Loose battery connection
• Damaged PCM

If KAPWR is interrupted to the PCM because of a battery or PCM disconnect, DTC can be generated on the first power-up.

P0605 - PCM Read Only Memory (ROM) error

The PCM ROM has been corrupted.

• An attempt was made to change the calibration
• Module programming error
• Physically damaged PCM

• Reprogram or update calibration
• Reprogram VID block (use as built data)
• Check for other DTC's or drive symptoms for further action

P0606 - Powertrain Control Module Internal Communication error

DTC P0606 indicates register readback (PCM internal Communications) error.

• Damaged PCM

P0606 - Electronic Throttle Control System Fault in combination with other DTCS, or Powertrain Control Module Internal Communication error for DTC Alone

DTC P0606 alone, indicates register readback (PCM internal Communications) error, for P0606 in combination with other Electronic Throttle Control DTCS, indicates a system fault. If the other DTCS are repaired, then should also be corrected.

• Damaged, or defective PCM
• Electronic Throttle Control system fault, DTC dependent.

P0622 - Generator Field Terminal Circuit Failure

The PCM monitors generator load from the generator/regulator in the form of frequency. The frequency range is determined by the temperature of the voltage regulator, where 97 percent indicates full load, below 6 percent indicates no load.

• GEN-MON circuit short to GND.
• GEN-MON circuit short to B+.
• GEN-MON circuit open.
• GEN-COM circuit short to GND.
• GEN-COM circuit short to B+.
• GEN-COM circuit open.
• ILC circuit short to GND.
• ILC circuit short to B+.
• ILC circuit open.
• ALI circuit short to GND.
• ALI circuit short to B+.
• ALI circuit open.
• Battery sense circuit open.
• Generator drive mechanism.
• Damaged generator/regulator assembly.
• Damaged PCM.

• Verify battery voltage is 14.5 V.
• Verify generator/regulator has correct part number.

P0645 - Wide Open Throttle A/C Cutout Primary Circuit Malfunction

NOTE: For applications that use a normally open relay to control the A/C clutch, the following description applies to the A/C clutch relay control circuit.
Monitors the wide open throttle A/C cutoff (WAC) circuit output from the PCM. The test fails if: When the PCM grounds the WAC circuit, excessive current draw is detected on the WAC circuit; or with the WAC circuit not grounded by the PCM, voltage is not detected on the WAC circuit (the PCM expects to detect VPWR voltage coming through the WAC relay coil to the WAC circuit).

• Open or shorted WAC circuit
• Damaged WAC relay (or CCRM)
• Open VPWR circuit to WAC relay
• Damaged PCM

• When the WACF PID reads YES, a fault is currently present
• An open circuit or short to ground can only be detected when the PCM is not grounding the circuit
• A short to power can only be detected when the PCM is grounding the circuit
• During KOEO and KOER self-test, the WAC circuit will be cycled ON and OFF
• Verify A/C and defrost were OFF during KOEO and KOER self-test (Check ACCS PID to verify)
• If vehicle is not equipped with A/C, P1460 can be ignored

P0660 - Intake Manifold Tuning Valve circuit Malfunction.

The IMTV system is monitored for failure during continuous, key ON engine OFF or key ON engine running self-test. The test fails when the signal on the monitor pin is more or less than an the expected calibrated range.

• IMTV signal circuit open, shorted to PWR GND or SIG RTN
• Damaged IMRC actuator
• Damaged PCM

An IMTVM PID reading may indicate a fault if available

P0703 - Brake Switch Circuit Input Malfunction

Indicates PCM did not receive a brake pedal position (BPP) input.

• Open or short in BPP circuit
• Open or short in stoplamp circuits
• Damaged PCM
• Malfunction in module(s) connected to BPP circuit. (Rear Electronic Module [REM] Windstar, LS6/LS8 and Thunderbird or Lighting Control Module (LCM) for Town Car)
• Damaged brake switch
• Misadjusted brake switch

Check for proper function of stoplamps. Using the scan tool, check BPP PID. Stoplamps and PID should toggle on and off with brake pedal activation.

P0704 - Clutch Pedal Position Switch Malfunction

When the clutch pedal is depressed the voltage goes to low. If the PCM does not see this change from high to low the DTC is set.

• CPP circuit short to PWR
• Damaged CPP switch
• CPP circuit open in the SIGRTN
• Damaged PCM

When depressing the CPP switch the voltage should cycle from 5.0V down.

P0720 - Insufficient input from Output Shaft Speed sensor

The output shaft speed sensor inputs a signal to the PCM, based on the speed of the output shaft of the transmission. The PCM compares this signal with the signal of the VSS or TCSS and determines correct tire size and axle gear ratio.

• OSS sensor circuit short to GND
• OSS sensor circuit short to PWR
• OSS sensor circuit open
• Damaged OSS sensor
• Damaged PCM

Verify sensor signal output varies with vehicle speed.

P0721 - Noise interference on Output Shaft Speed sensor signal

The output shaft speed sensor signal is very sensitive to noise. This noise distorts the input to the PCM.

• Wiring misrouted
• After market add-on
• Wiring damaged
• Wiring insulation wear

• Check routing of harness.
• Check wiring and connector for damage.

P0722 - No signal from Output Shaft Speed sensor

The output shaft speed sensor failed to provide a signal to the PCM upon initial movement of vehicle.

• Damaged OSS connector
• Damaged OSS sensor, or not installed properly
• Harness intermittently shorted or open

P0723 - Output Shaft Speed sensor circuit intermittent failure

The output shaft speed sensor signal to the PCM is irregular or interrupted.

• Harness connector not properly seated
• Harness intermittently shorted, or open
• Harness connector damaged
• OSS sensor damaged, or not installed properly

• Verify harness and connector integrity
• Verify OSS sensor proper installation

P0812 - Reverse Switch (RS) input circuit malfunction

The DTC indicates that the voltage is high when it should be low.

• Transmission shift not indicating neutral while in KOEO Self-Test
• RS circuit short to PWR
• Damaged reverse switch
• RS circuit open or short to SIGRTN
• Damaged PCM

Check RS PID while exercising shift lever in and out of reverse.

P1000 - OBD (On Board Diagnostic) System Readiness Test Not Complete

The OBD monitors are performed during the OBD Drive Cycle. The P1000 will be stored in continuous memory if any of the OBD monitors do not complete their full diagnostic check.

• Vehicle is new from the factory
• Battery or PCM had recently been disconnected
• An OBD monitor failure had occurred before completion of an OBD drive cycle
• PCM DTCs have recently been cleared with a scan tool
• PTO circuit is shorted to VPWR or B+ or PTO is on during testing

The Ford P1000, inspection/maintenance (I/M) readiness function is part of the PCM strategy. A battery disconnection or clearing codes using a scan tool results in the various I/M readiness bits being set to a "not-ready" condition. As each non-continuous OBD monitor completes a full diagnostic check, the I/M readiness bit associated with that monitor is set to a "ready" condition. This may take 1 or 2 drive cycles based on whether malfunctions are detected or not. The readiness bits for comprehensive component monitoring, misfire and fuel system monitoring are considered complete once all the non-continuous monitors have been evaluated. Because the EVAP system monitor requires certain ambient conditions to run, special logic can "bypass" the monitor for purpose of clearing the EVAP system I/M readiness bit due to continued presence of these extreme conditions.
Note: The P1000 does not need to be cleared from the PCM except to pass an I/M test.

P1001 - KOER Not Able To Complete, KOER Aborted

This Non-MIL (Malfunction Indicator Lamp) code will be set when Key On Engine Running (KOER) Self-Test does not complete in the time intended.

• Incorrect Self-Test Procedure.
• Unexpected response from Self-Test monitors.
• rpm out of specification.

P1100 - Mass Air Flow (MAF) Sensor Intermittent

The MAF sensor circuit is monitored by the PCM for sudden voltage (or air flow) input change through the comprehensive component monitor (CCM). If during the last 40 warm-up cycles in key ON engine running the PCM detects a voltage (or air flow) change beyond the minimum or maximum calibrated limit, a continuous memory diagnostic trouble code (DTC) is stored.

• Poor continuity through the MAF sensor connectors
• Poor continuity through the MAF sensor harness
• Intermittent open or short inside the MAF sensor.

While accessing the MAF V PID on the scan tool, lightly tap on the MAF sensor or wiggle the MAF sensor connector and harness. If the MAF V PID suddenly changes below 0.23 volt or above 4.60 volts, an intermittent fault is indicated.

P1101 - Mass Air Flow (MAF) Sensor Out of Self-Test Range

The MAF sensor circuit is monitored by the PCM for an out of range air flow (or voltage) input. If during key ON engine OFF the air flow voltage signal is greater than 0.27 volts the test fails. Likewise, if during key ON engine running, an air flow voltage signal is not within 0.46 volt to 2.44 volts, the test fails.

• Low battery charge
• MAF sensor partially connected
• MAF sensor contamination
• PWR GND open to MAF sensor
• MAF RTN circuit open to PCM
• Damaged MAF sensor
• Damaged PCM

A MAF V PID reading greater than 0.27 volts (KOEO) or a MAF V PID reading outside the 0.46 volt to 2.44 volts range (KOER) indicates a hard fault.

P1112 - Intake Air Temperature (IAT) Sensor Intermittent

Indicates IAT sensor signal was intermittent during the comprehensive component monitor.

• Damaged harness
• Damaged sensor
• Damaged harness connector
• Damaged PCM

Monitor IAT on scan tool, look for sudden changes in reading when harness is wiggled or sensor is tapped.

P1114 - Intake Air Temperature 2 Circuit Low Input

Indicates the sensor signal is less than Self-Test minimum. The IAT2 sensor minimum is 0.2 volts.

• Grounded circuit in harness
• Improper harness connection
• Damaged sensor
• Damaged PCM

Monitor IAT2 PID. Typical IAT2 temperature should be greater than IAT1.

P1115 - Intake Air Temperature 2 Circuit High Input

Indicates the sensor signal is greater than Self-Test maximum. The IAT2 sensor maximum is 4.6 volts.

• Open circuit in harness
• Sensor signal short to power
• Improper harness connection
• Damaged sensor
• Damaged PCM

Monitor IAT2 PID. Typical IAT2 temperature should be greater than IAT1.

P1116 - Engine Coolant Temperature (ECT) Sensor Out of Self-Test Range

Indicates the ECT sensor is out of Self-Test range. Correct range is 0.3 to 3.7 volts.

• Overheating condition
• Malfunctioning thermostat
• Damaged ECT sensor
• Low engine coolant
• Damaged harness connector
• Damaged PCM

Engine coolant temperature must be greater than 10°C (50°F) to pass the KOEO Self-Test and greater than 82°C (180°F) to pass the KOER Self-Test.

P1117 - Engine Coolant Temperature (ECT) Sensor Intermittent

Indicates ECT circuit became intermittently open or shorted while engine was running. Note on some vehicles that are not equipped with an ECT sensor, CHT can be used and can set this DTC.

• Damaged harness
• Damaged sensor
• Damaged PCM
• Damaged harness connector
• Low engine coolant

Monitor ECT or CHT on scan tool, look for sudden changes in reading when harness is wiggled or sensor is tapped.

P1120 - Throttle Position (TP) Sensor Out of Range Low (RATCH too Low)

The TP sensor circuit is monitored by the PCM for a low TP rotation angle (or voltage) input below the closed throttle position through the comprehensive component monitor (CCM). If during key ON engine OFF or key ON engine running the TP rotation angle (or voltage) remains within the calibrated self-test range but falls between 3.42 and 9.85% (0.17 and 0.49 volt), the test fails.

• TP circuit with frayed wires
• Corrosion on TP circuit connectors
• VREF open to TP sensor
• VREF short to SIG RTN
• TP sensor loose pins

A TP PID (TP V PID) between 3.42 and 9.85% (0.17 and 0.49 volt) in key ON engine OFF, continuous memory or key ON engine running indicates a hard fault.

P1121 - Throttle Position (TP) Sensor Inconsistent with MAF Sensor

The PCM monitors a vehicle operation rationality check by comparing sensed throttle position to mass air flow readings. If during key ON engine running self-test the comparison of the TP sensor and MAF sensor readings are not consistent with calibrated load values, the test fails and a diagnostic trouble code is stored in continuous memory.

• Air leak between MAF sensor and throttle body
• TP sensor not seated properly
• Damaged TP sensor
• Damaged MAF sensor

Drive vehicle and exercise throttle and TP sensor in all gears. A TP PID (TP V PID) less than 4.82 % (0.24 volt) with a LOAD PID greater than 55% or a TP V PID greater than 49.05% (2.44 volts) with a LOAD PID less than 30% indicates a hard fault.

P1124 - Throttle Position (TP) Sensor Out of Self-Test Range

The TP sensor circuit is monitored by the PCM for an out of range TP rotation angle (or voltage) input. If during key ON engine OFF or key ON engine running the TP rotation angle (or voltage) reading is less than 13.27% (0.66 volt) or greater than 23.52% (1.17 volts), the test fails.

• Binding or bent throttle linkage
• TP sensor not seated properly
• Throttle plate below closed throttle position
• Throttle plate/screw misadjusted
• Damaged TP sensor
• Damaged PCM

A TP PID (TP V PID) reading not between 13.27 and 23.52% (0.66 and 1.17 volts) in key ON engine OFF or key ON engine running indicates a hard fault.

P1125 - Throttle Position (TP) Sensor Intermittent

The TP sensor circuit is monitored by the PCM for sudden TP rotation angle (or voltage) input change through the comprehensive component monitor (CCM). If during the last 80 warm-up cycles in key ON engine running the PCM detects a TP rotation angle (or voltage) changes beyond the minimum or maximum calibrated limit, a continuous diagnostic trouble code (DTC) is stored.

• Poor continuity through the TP sensor connectors
• Poor continuity through the TP harness
• Intermittent open or short inside the TP sensor

While accessing the TP V PID on the scan tool, lightly tap on the TP sensor or wiggle the TP sensor connector and harness. If the TP V PID suddenly changes below 0.49 volt or above 4.65 volts, an intermittent fault is indicated.

P1127 - Exhaust Not Warm Enough, Downstream Sensor Not Tested

The HEGO monitor uses an exhaust temperature model to determine when the HO2S heaters are cycled ON. The test fails when the inferred exhaust temperature is below a minimum calibrated value.

• Engine not operating long enough prior to performing KOER self-test.
• Exhaust system too cool.

Monitor HO2S Heater PIDs to determine their ON/OFF state. DTC P1127 will be present if the exhaust is not hot.

P1128 - Upstream Oxygen Sensors Swapped from Bank to Bank (HO2S-11-21)

The HEGO monitor checks and determines if the HO2S signal response for a fuel shift corresponds to the correct engine bank. The test fails when a response from the HO2S(s) being tested is not indicated.

• Crossed HO2S harness connectors (upstream).
• Crossed HO2S wiring at the harness connectors (upstream).
• Crossed HO2S wiring at the 104-pin harness connectors (upstream).

P1129 - Downstream Oxygen Sensors Swapped from Bank to Bank (HO2S-12-22)

The HEGO monitor checks and determines if the HO2S signal response for a fuel shift corresponds to the correct engine bank. The test fails when a response from the HO2S(s) being tested is not indicated.

• Crossed HO2S harness connectors (downstream).
• Crossed HO2S wiring at the harness connectors (downstream).
• Crossed HO2S wiring at the 104-pin harness connectors (downstream).

P1130 - Lack of HO2S-11 Switch, Fuel Trim at Limit

The HEGO Sensor is monitored for switching. The test fails when the HO2S fails to switch due to circuit or fuel at or exceeding a calibrated limit.

• Electrical:
• Short to VPWR in harness or HO2S
• Water in harness connector
• Open/Shorted HO2S circuit
• Corrosion or poor mating terminals and wiring
• Damaged HO2S
• Damaged PCM
• Fuel System:
• Excessive fuel pressure
• Leaking/contaminated fuel injectors
• Leaking fuel pressure regulator
• Low fuel pressure or running out of fuel
• Vapor recovery system
• Induction System:
• Air leaks after the MAF
• Vacuum Leaks
• PCV system
• Improperly seated engine oil dipstick
• EGR System:
• Leaking gasket
• Stuck EGR valve
• Leaking diaphragm or EVR
• Base Engine:
• Oil overfill
• Cam timing
• Cylinder compression
• Exhaust leaks before or near the HO2S(s)

A fuel control HO2S PID switching across 0.45 volt from 0.2 to 0.9 volt indicates a normal switching HO2S.

P1131 - Lack of HO2S-11 Switch, Sensor Indicates Lean

A HEGO sensor indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time.

See Possible Causes for P1130

P1132 - Lack of HO2S-11 Switch, Sensor Indicates Rich

A HEGO sensor indicating rich at the end of a test is trying to correct for an over-lean condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time.

See Possible Causes for P1130

P1137 - Lack of HO2S-12 Switch, Sensor Indicates Lean

The downstream HO2S sensors are forced rich and lean and monitored by the PCM. The test fails if the PCM does not detect the output of the HO2S in a calibrated amount of time.

• Pinched, shorted, and corroded wiring and pins
• Crossed sensor wires
• Exhaust leaks
• Contaminated or damaged sensor

P1138 - Lack of HO2S-12 Switch, Sensor Indicates Rich

See DTC P1137

P1150 - Lack of HO2S-21 Switch, Fuel Trim at Limit

See DTC P1130

P1151 - Lack of HO2S-21 Switch, Sensor Indicates Lean

A HEGO sensor indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when fuel control system no longer detects switching for a calibrated amount of time.

See Possible Causes for P1130

P1152 - Lack of HO2S-21 Switch, Sensor Indicates Rich

A HEGO sensor indicating rich at the end of a test is trying to correct for an over-lean condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time.

See Possible Causes for P1130

P1157 - Lack of HO2S-22 Switch, Sensor Indicates Lean

See DTC P1137

P1158 - Lack of HO2S-22 Switch, Sensor Indicates Rich

See DTC P1137

P1168 - Fuel Rail Pressure Sensor in Range But Low

The comprehensive component monitor (CCM) monitors the FRP pressure for acceptable fuel pressure. The test fails when the fuel pressure falls below a calibrated value.

• Low fuel pressure
• Damaged FRP sensor
• Excessive resistance in circuit
• Low or no fuel

• A FRP PID value below 551 kpa (80 psi) indicates a failure
• Low or no fuel
• A FRP PID value greater than 896 kpa (130 psi) indicates a failure

P1169 - Fuel Rail Pressure (FRP) Sensor in Range But High

The comprehensive component monitor (CCM) monitors the FRP pressure for acceptable fuel pressure. The test fails when the fuel pressure falls below or exceeds a minimum/maximum calibrated value for a calibrated period of time.

• High fuel pressure
• Low fuel pressure
• Damaged FRP sensor
• Excessive resistance in circuit

P1180 - Fuel Delivery System - Low

The PCM receives fuel tank pressure (FTP) information from the natural gas module (NG), which uses the information to infer fuel rail pressure (FRP). The test fails when the inferred pressure is less than a minimum calibrated value.

• Restriction in the fuel line
• Plugged fuel filter

P1181 - Fuel Delivery System - High

The PCM receives fuel tank pressure (FTP) information from the natural gas module (NG), which uses the information to infer fuel rail pressure (FRP). The test fails when the inferred pressure is higher than a maximum calibrated value.

• Fuel pressure regulator

P1184 - Engine Oil Temperature (EOT) Sensor Out of Self-Test Range

Indicates EOT signal was out of Self-Test range.

• Damaged harness
• Damaged sensor
• Damaged harness connector
• Damaged PCM

Engine should be at operating temperature before running self-test.

P1229 - Supercharger Intercooler Pump (ICP) Pump Not Operating

The ICP DTC will be set when the PCM is calling for the pump to be operating but no current is being detected.

• Pump motor open circuited
• Pump relay coil open
• Open circuit between relay and pump
• Damaged PCM
• Pump motor shorted
• Open circuit between PCM and relay
• Poor pump ground connection

Check for voltage at relay, check fuse in power feed, check ground connection of pump motor, PID reading is on/off.

P1232 - Low Speed Fuel Pump Primary Circuit Malfunction

The PCM monitors the low speed fuel pump (LFP) primary circuit output from the PCM. The test fails if: When the LFP circuit is commanded on (grounded), excessive current draw is detected on the LFP circuit; or when the LFP circuit is commanded off, voltage is not detected on the LFP circuit (the PCM expects to detect VPWR voltage coming through the low speed fuel pump relay coil to the LFP circuit).

• Open or shorted low fuel pump (LFP) circuit
• Open VPWR to low speed fuel pump relay
• Damaged low speed fuel pump relay
• Damaged PCM

• An open circuit or short to ground can only be detected with the low speed fuel pump.
• A short to power can only be detected with the low speed fuel pump commanded on.
• During KOEO and KOER Self-Test, the low speed fuel pump output command will be cycled on and off.

P1233 - Fuel System Disabled or Offline

LS6/LS8 and Thunderbird:
For LS6/LS8 and Thunderbird, P1233 indicates the PCM is not receiving the fuel level information on SCP from the rear electronics module (REM). Refer to Workshop Manual Section 418 for REM (REAR ELECTRONICS MODULE) self-test/diagnostics.
All Others:
The PCM monitors the fuel pump monitor (FPM) circuit from the fuel pump driver module (FPDM). With the key on, the FPDM continuously sends a duty cycle signal to the PCM through the FPM circuit. The test fails if the PCM stops receiving the duty cycle signal.

• Inertia fuel shutoff (IFS) switch needs to be reset
• Open FPDM ground circuit
• Open or shorted FPM circuit
• Damaged IFS switch
• Damaged FPDM
• Damaged PCM
• Also for Escort and Mustang:
• Open FPDM PWR circuit
• Open B+ circuit to constant control relay module (CCRM) pin 11
• Open ground to CCRM pin 18 (Mustang)
• Damaged CCRM

The PCM expects to see one of the following duty cycle signals from the FPDM on the FPM circuit: 1) 50% (500 msec on, 500 msec off), all OK. 2) 25% (250 msec on, 750 msec off), FPDM did not receive a fuel pump (FP) duty cycle command from the PCM, or the duty cycle that was received was invalid. 3) 75% (750 msec ON, 250 OFF), the FPDM has detected a fault in the circuits between the FPDM and the fuel pump.

P1234 - Fuel System Disabled or Offline

See DTC P1233 P1234 is identical to P1233 except P1234 will not illuminate the MIL.

P1235 - Fuel Pump Control Out Of Range

Note: For LS6/LS8 and Thunderbird, the FPDM functions are incorporated in the Rear Electronics Module (REM). Also, the REM does not use a FPM circuit. Diagnostic information will be sent through SCP.
P1235 indicates that the FPDM has detected an invalid or missing FP circuit signal from the PCM. The FPDM will send a message to the PCM through the FPM circuit, indicating that this failure has been detected. The PCM will set the DTC when the message is received.

• FP circuit open or shorted
• Electronic Throttle Control (ETC) system concern (check for ETC DTC P2105).
• Damaged FPDM.
• Damaged PCM

• The FPDM sends a 25% duty cycle (250 msec ON, 750 msec OFF) through the FPM circuit to the PCM while the fault is being detected by the FPDM. If the fault is no longer detected, the PDM will return to sending an "all OK" (50% duty cycle) message to the PCM. The PCM will keep P1235 stored in Continuous Memory.
• For LS6/LS8 and Thunderbird, check if Electronic Throttle Control (ETC) DTC P2105 is present. An ETC system concern could cause a P1235, and should be diagnosed first.

P1236 - Fuel Pump Control Out Of Range

See DTC P1235 P1236 is identical to P1235 except P1236 will not illuminate the MIL.

P1237 - Fuel Pump Secondary Circuit Malfunction

Note: For LS6/LS8 and Thunderbird, the FPDM functions are incorporated in the rear electronics module (REM). Also, the REM does not use a FPM circuit. Diagnostic information will be set through SCP.
P1237 indicates that the FPDM has detected a fuel pump secondary circuit fault. The FPDM will send a message to the PCM through the FPM circuit, indicating that this failure has been detected. The PCM will set the DTC when the message is received.

• Open or shorted FP PWR circuit
• Open FP RTN circuit to FPDM
• Open or shorted circuit in the fuel pump
• Locked fuel pump rotor
• Damaged FPDM
• For LS6/LS8 and Thunderbird, circuits associated with the Fuel Pump relay

• The FPDM sends a 75% duty cycle (750 msec ON, 250 msec OFF) through the FPM circuit to the PCM while the fault is being detected by the FPDM. If the fault is no longer detected, the PCM will return to sending an "all OK" (50% duty cycle) message to the PCM. The PCM will keep P1237 stored in Continuous Memory.
• The FPDM controls pump speed by supplying a "variable" ground on the RTN circuit.

P1238 - Fuel Pump Secondary Circuit Malfunction

See DTC P1237 P1238 is identical to P1237 except P1238 will not illuminate the MIL.

P1244 - Generator Load Input High

The PCM monitors generator load from the generator/regulator in the form of frequency. The fault indicates the input is lower than the load should be in normal operation. The load input could be high when a battery short to ground exists.

• Generator input circuit shorted to battery power
• B+ open prior to start-up
• Open I-line prior to start-up
• Damaged PCM

• Verify battery voltage is 14.5V.
• Verify generator/regulator has the correct part number.

P1245 - Generator Load Input Low

The PCM monitors generator load from the generator/regulator in the form of frequency. The fault indicates the input is lower than the load should be in normal operation. The load input could be low when no generator output exists.

• Generator circuit short to GND
• Open B+ wire during operation
• Low system voltage
• Broken generator belt
• Damaged generator/regulator assembly
• Damaged PCM

• Verify battery voltage is 14.5V.
• Verify generator/regulator has the correct part number.

P1246 - Generator Load Input Failed

The PCM monitors generator load from the generator/regulator in the form of frequency. The frequency range is determined by the temperature of the voltage regulator where 97% represents full load, below 6% means no load.

• Generator circuit short to GND
• Generator circuit short to PWR
• Generator circuit open
• Generator drive mechanism
• Damaged generator/regulator assembly
• Damaged PCM

• Verify battery voltage is 14.5V.
• Verify generator/regulator has the correct part number.

P1260 - Theft Detected - Vehicle Immobilized

Indicates that the passive anti-theft system (PATS) has determined a theft condition existed and the engine is disabled. This DTC is a good indicator to check the PATS for DTCs.

• Previous theft condition
• Anti-Theft System failure

Theft indicator flashing rapidly or on solid when ignition switch is in the ON position. Check anti-theft system for DTCs. Typical vehicle symptoms are: Start/Stall or Crank/No Start. NOTE: No crank symptom only on vehicles equipped with PATS starter disable feature.

P1270 - Engine RPM/Vehicle Speed Limiter

Indicates the vehicle has been operated in a manner, which caused the engine or vehicle to exceed a calibration limit. The engine rpm and vehicle speed are continuously monitored and evaluated by the PCM. The DTC is set when the rpm or vehicle speed falls out of a calibrated range.

• Wheel slippage (water, ice, mud and snow)
• Excessive engine rpm in Neutral or operated in the wrong transmission gear
• Vehicle driven at a high rate of speed

The DTC indicates the vehicle has been operated in a manner, which caused the engine or vehicle speed to exceed a calibrated limit.

P1285 - Cylinder Head Over Temperature Sensed

Indicates an engine overheat condition was sensed by the cylinder head temperature sensor.

• Low engine coolant level
• Base engine concerns
• Engine cooling system concerns
• CHT sensor concern

On some applications when this fault occurs the Engine Temperature warning indicator will illuminate and/or force the temperature gauge to full H (Hot) zone by grounding the engine temperature warning circuit.

P1288 - Cylinder Head Temperature (CHT) Sensor Circuit Out of Self-Test Range

Indicates the CHT sensor is out of Self-Test range. Engine is not at normal operating temperature.

• Cold engine
• Engine overheating
• Damaged harness connector
• Damaged PCM
• Low engine coolant level
• Damaged CHT sensor

Bring engine to operating temperature. If cold, re-run self-test. If engine over-heats check cooling system.

P1289 - Cylinder Head Temperature (CHT) Sensor Circuit High Input

Indicates a CHT sensor circuit malfunction (open).

• Open circuit in CHT harness
• Damaged CHT sensor
• Improper harness connection
• Damaged PCM

CHT V PID reading greater than 4.6 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault. Note:  P0118 may also be reported when this DTC is set, either of these DTC's will activate the MIL light.

P1290 - Cylinder Head Temperature (CHT) Sensor Circuit Low Input

Indicates a CHT sensor circuit malfunction (shorted).

• Grounded circuit in CHT harness
• Damaged CHT sensor
• Improper harness connection
• Damaged PCM

CHT V PID reading less than 0.2 volts with key ON and engine OFF or during any engine operating mode indicates a hard fault. Note: P0117 may also be reported when this DTC is set, either of these DTC's will activate the MIL light.

P1299 - Cylinder Head Over Temperature Protection Active

Indicates an engine overheat condition was detected by the cylinder head temperature (CHT) sensor. An FMEM Strategy called Fail-safe Cooling was activated to cool the engine.

• Engine cooling system concerns
• Low engine coolant level
• Base engine concerns

P1309 - Misfire Monitor Disabled

When the misfire monitor is disabled, usually due to the input signal generated by the camshaft position (CMP) sensor, by sensing the passage of teeth from the CMP wheel.

• Camshaft position sensor
• Powertrain Control Module
• ECT, MAF, and CKP sensors

Verify the CMP is installed correctly and not out of synchronization.

P1336 - CKP and or CMP Input Signal to PCM Concerns

Input Signal to PCM from CKP Sensor and or CMP Sensor erratic.

• Damaged PCM
• Damaged CKP sensor
• Damaged CMP sensor
• Base Engine Concerns
• Harness Concerns

Harness routing, alterations, improper shielding, or electrical interference from other improperly functioning systems.

P1380 - Variable Cam Timing Solenoid A Circuit Malfunction (Bank 1)

The comprehensive component monitor(CCM) monitors the VCT circuit to the PCM for high and low voltage. If during testing voltage was to fall below a calibrated limit a calibrated amount of time the test will fail.

• Open or short VCT circuit
• Open VPWR circuit
• Damaged PCM
• Open or short VCT solenoid valve

DTC P1380 is a VCT circuit check. Testing should include wires, solenoid coil and PCM.

P1381 - Variable Cam Timing Over-advanced (Bank 1)

The comprehensive component monitor (CCM) monitors the VCT position for an over-advanced camshaft timing. The test fails when the camshaft timing exceeds a maximum calibrated value or remains in an advanced position.

• Cam timing improperly set
• No oil flow to the VCT piston chamber
• Low oil pressure
• VCT solenoid valve stuck closed
• Camshaft advance mechanism binding (VCT unit)

DTC P1381 is a check of the VCT unit. Engine will idle rough, hard starting and may stall. Diagnostics and repair for the VCT unit are located in the Workshop Manual. Check the operation of the VCT solenoid and check for a stuck or sticking solenoid valve caused by contamination. If the valve is stuck, check spider bracket for contamination prior to solenoid replacement.

P1383 - Variable Cam Timing Over-retarded (Bank 1)

The comprehensive component monitor (CCM) monitors the VCT position for over-retarded camshaft timing. The test fails when the camshaft timing exceeds a maximum calibrated value or remains in an retarded position.

• Cam timing improperly set
• Continuous oil flow to the VCT piston chamber
• VCT solenoid valve stuck open
• Camshaft advance mechanism binding (VCT unit)

DTC P1383 is a check of the VCT unit. Engine will idle rough, hard starting and may stall. Diagnostics and repair for the VCT unit are located in the Workshop Manual. Check the operation of the VCT solenoid and check for a stuck or sticking solenoid valve caused by contamination. If the valve is stuck, check spider bracket for contamination prior to solenoid replacement.

P1385 - Variable Cam Timing Solenoid A Circuit Malfunction (Bank 2)

The comprehensive component monitor(CCM) monitors the VCT circuit to the PCM for high and low voltage. If during testing voltage was to fall below a calibrated limit a calibrated amount of time the test will fail.

• Open or short VCT circuit
• Open VPWR circuit
• Damaged PCM
• Open or short VCT solenoid valve

DTC P1385 is a VCT circuit check. Testing should include wires, solenoid coil and PCM.

P1386 - Variable Cam Timing Over-advanced (Bank 2)

The comprehensive component monitor (CCM) monitors the VCT position for an over-advanced camshaft timing. The test fails when the camshaft timing exceeds a maximum calibrated value or remains in an advanced position.

• Cam timing improperly set
• No oil flow to the VCT piston chamber
• Low oil pressure
• VCT solenoid valve stuck closed
• Camshaft advance mechanism binding (VCT unit)

DTC P1386 is a check of the VCT unit. Engine will idle rough, hard starting and may stall. Diagnostics and repair for the VCT unit are located in the Workshop Manual. Check the operation of the VCT solenoid and check for a stuck or sticking solenoid valve caused by contamination. If the valve is stuck, check spider bracket for contamination prior to solenoid replacement.

P1388 - Variable Cam Timing Over-retarded (Bank 2)

The comprehensive component monitor (CCM) monitors the VCT position for over-retarded camshaft timing. The test fails when the camshaft timing exceeds a maximum calibrated value or remains in an retarded position.

• Cam timing improperly set
• Continuous oil flow to the VCT piston chamber
• VCT solenoid valve stuck open
• Camshaft advance mechanism binding (VCT unit)

DTC P1388 is a check of the VCT unit. Engine will idle rough, hard starting and may stall. Diagnostics and repair for the VCT unit are located in the Workshop Manual. Check the operation of the VCT solenoid and check for a stuck or sticking solenoid valve caused by contamination. If the valve is stuck, check spider bracket for contamination prior to solenoid replacement.

P1400 - DPF EGR Sensor Circuit Low Voltage Detected

The EGR monitor checks the DPF EGR sensor signal to the PCM for low voltage. The test fails when the average voltage to the PCM drops to a voltage less than the minimum calibrated value.

• DPFEGR circuit short to GND
• Damaged DPF EGR sensor
• VREF short to GND
• Damaged PCM

A DPF EGR PID reading less than 0.2 volt with the key ON and engine OFF or running, indicates a hard fault.

P1401 - DPF EGR Sensor Circuit High Voltage Detected

The EGR monitor checks the DPF EGR sensor signal to the PCM for high voltage. The test fails when the average voltage to the PCM goes to a voltage greater than the maximum calibrated value.

• DPF EGR circuit open
• VREF short to PWR
• Damaged DPF EGR sensor
• DPFEGR circuit short to PWR
• SIG RTN circuit open
• Damaged PCM

A DPF EGR PID reading greater than 4.5 volts with the key ON and engine OFF or running, indicates a hard fault.

P1405 - DPF EGR Sensor Upstream Hose Off or Plugged

While driving, the EGR monitor commands the EGR valve closed and checks the differential pressure across the EGR orifice. The test fails when the signal from the DPF EGR sensor indicates EGR flow is in the negative direction.

• Upstream hose is disconnected
• Upstream hose is plugged (ice)
• Plugged or damaged EGR tube

• Look for signs of water or icing in hose
• Verify hose connection and routing (no excessive dips)
• Verify DPF EGR sensor proper mounting and function (view DPF EGR PID while applying and releasing vacuum directly to sensor with a hand pump)

P1406 - DPF EGR Sensor Downstream Hose Off or Plugged

While driving, the EGR monitor commands the EGR valve closed and checks the differential pressure across the EGR orifice. The test fails when the signal from the DPF EGR sensor continues to indicate EGR flow even after the EGR valve is commanded closed.

• Downstream hose is disconnected
• Downstream hose is plugged (ice)
• Plugged or damaged EGR tube

• Look for signs of water or icing in hose
• Verify connection and routing (no excessive dips)
• Verify DPF EGR sensor proper mounting and function (view DPFEGR PID while applying and releasing vacuum directly to sensor with a hand pump)

P1408 - EGR Flow Out of Self-Test Range (Non MIL)

This test is performed during the KOER on demand self-test only. The EGR system is commanded ON at a fixed engine speed. The test fails and the DTC is output when the measured EGR flow falls above or below the required calibration .

For vacuum activated systems, see Possible Causes for P0401. For electric motor system, see Possible Causes P0400.

For Electric EGR, use the output state control function of the scan tool and monitor the MAP PID (MAP) and the EEGR PID (EGRMDSD) while commanding the EEGR on. If EGR is introduced into the engine at idle, the rpm will drop or stall out. For vacuum systems see Diagnostic Aids for P0401.

P1409 - EGR Vacuum Regulator Solenoid Circuit Malfunction

This test checks the electrical function of the EGRVR solenoid. The test fails when the EGRVR circuit voltage is either too high or too low when compared to the expected voltage range. The EGR system must be enabled for the test to be completed.

• EGRVR circuit open
• VPWR open to EGRVR solenoid
• EGRVR circuit short to VPWR or GND
• Damaged EGRVR solenoid
• Damaged PCM

The EGR vacuum regulator solenoid resistance is from 26 to 40 ohms.

P1411 - Secondary Air Injection (AIR) system downstream flow

The secondary air injection system does not detect the presence of air in the exhaust when introduced by the secondary air injection system

• Electric AIR Pump
• Hose from AIR pump leak
• AIR bypass solenoid leak/blocked
• Hose from AIR pump blocked
• AIR bypass solenoid stuck open/closed

In order to test the AIR pump, it must be capable of driving the HO2S lean.

P1432 - Thermostat Heater Control (THTRC) Circuit Failure

The Comprehensive component monitor (CCM) monitors the THTRC circuit to the PCM for high and low voltage. If during testing; voltage was to fall below a calibrated limit for a calibrated amount of time the test will fail and set the DTC and MIL.

• Open or shorted THTRC circuit
• Open VPWR
• Open or shorted thermostat assembly
• Damaged PCM

DTC P1432 is a THTRC circuit check. Testing should include wire harness, thermostat heater and PCM.

P1436 - A/C Evaporator Temperature (ACET) Circuit Low Input

Indicates the ACET signal input is less than Self-Test minimum. Self-Test minimum is 0.13 volts.

• ACET circuit short to ground or SIG RTN
• Damaged ACET sensor
• Damaged PCM

The PCM sources a low current 5 volts on the ACET circuit (this voltage can be measured with the sensor disconnected). As A/C evaporator air temperature changes, the ACET circuit resistance to SIG RTN (ground) changes (which changes the voltage the PCM detects). When the ACET signal is detected below the Self-Test minimum, check for shorts to SIG RTN or ground, which would pull the voltage low.

P1437 - A/C Evaporator Temperature (ACET) Circuit High Input

Indicates the ACET signal input is greater than Self-Test minimum. Self-Test maximum is 4.5 volts.

• ACET circuit open
• SIG RTN circuit open to ACET sensor
• ACET circuit short to power (VREF)
• Damaged ACET sensor
• Damaged PCM

The PCM sources a low current 5 volts on the ACET circuit (this voltage can be measured with the sensor disconnected). As A/C evaporator air temperature changes, the ACET circuit resistance to SIG RTN (ground) changes (which changes the voltage the PCM detects). When the ACET signal is detected above the Self-Test maximum, check for open cirucits (ACET or SIG RTN), which would cause the voltage to remain high. Although not as probable, also check for a short to power (VREF).

P1443 - Very Small Or No Purge Flow Condition

A fuel tank pressure change greater than a minus (-) 7 inches of H ₂ O in 30 seconds has occurred with purge (fuel vapor) flow less than 0.02 pounds per minute.

• Blocked fuel vapor hose between EVAP canister purge valve and FTP sensor.
• Blocked fuel vapor hose between EVAP canister purge valve and engine intake manifold.
• Blocked vacuum hose between EVAP canister purge valve-solenoid and engine intake manifold.
• EVAP canister purge valve stuck closed (mechanically).

Check for blockages between the fuel tank, EVAP canister purge valve and engine intake manifold. Check obstructions in the EVAP canister purge valve diaphragm and ports.

P1450 - Unable to Bleed Up Fuel Tank Vacuum

Monitors the fuel vapor vacuum and pressure in the fuel tank. The system failure occurs when the EVAP running loss monitor detects excessive fuel tank vacuum with the engine running (but not at idle).

• Blockages or kinks in EVAP canister tube or EVAP canister purge outlet tube (between fuel tank, EVAP canister purge valve and EVAP canister)
• Fuel filler cap stuck closed (no vacuum relief)
• Contaminated fuel vapor elbow on EVAP canister
• Restricted EVAP canister
• CV solenoid stuck open (partially or fully)
• Plugged CV solenoid filter
• EVAP canister purge valve stuck open
• VREF circuit open (harness near FTP sensor, FTP sensor or PCM)
• Damaged FTP sensor

P1451 - EVAP Control System Canister Vent Solenoid Circuit Malfunction

Monitors the canister vent (CV) solenoid circuit for an electrical failure. The test fails when the signal moves outside the minimum or maximum allowable calibrated parameters for a specified canister vent duty cycle by PCM command.

• VPWR circuit open
• CV solenoid circuit shorted to PWR GND or CHASSIS GND
• Damaged CV solenoid
• CV solenoid circuit open
• CV solenoid circuit shorted to VPWR
• Damaged PCM

To verify normal function, monitor the EVAP canister vent solenoid signal PID EVAPCV and the signal voltage (PCM control side). With the valve open, EVAPCV will indicate 0 percent duty cycle and the voltage approximately equal to battery voltage. When the valve is commanded fully closed, EVAPCV will indicate 100% duty cycle and a voltage drop of 4 volts minimum is normal. Output test mode may be used to switch output ON/OFF to verify function.

P1460 - Wide Open Throttle A/C Cutout Primary Circuit Malfunction

NOTE: For applications that use a normally open relay to control the A/C clutch, the following description applies to the A/C clutch relay control circuit.
Monitors the wide open throttle A/C cutoff (WAC) circuit output from the PCM. The test fails if: When the PCM grounds the WAC circuit, excessive current draw is detected on the WAC circuit; or with the WAC circuit not grounded by the PCM, voltage is not detected on the WAC circuit (the PCM expects to detect VPWR voltage coming through the WAC relay coil to the WAC circuit).

• Open or shorted WAC circuit
• Damaged WAC relay (or CCRM)
• Open VPWR circuit to WAC relay
• Damaged PCM

• When the WACF PID reads YES, a fault is currently present
• An open circuit or short to ground can only be detected when the PCM is not grounding the circuit
• A short to power can only be detected when the PCM is grounding the circuit
• During KOEO and KOER self-test, the WAC circuit will be cycled ON and OFF
• Verify A/C and defrost were OFF during KOEO and KOER self-test (Check ACCS PID to verify)
• If vehicle is not equipped with A/C, DTC P1460 can be ignored

P1461 - Air Conditioning Pressure Sensor (ACP) Sensor High Voltage Detected

ACP inputs a voltage to the PCM. If the voltage is above a calibrated level the DTC will set.

• ACP sensor circuit short to PWR
• ACP circuit open
• Damaged PCM
• ACP circuit short to VREF
• ACP circuit short to SIGRTN
• Damaged ACP sensor

Verify VREF voltage between 4.0 and 6.0V.

P1462 - Air Conditioning Pressure Sensor (ACP) Sensor Low Voltage Detected

ACP inputs a voltage to the PCM. If the voltage is below the calibrated level the DTC will set.

• ACP circuit short to GND or SIGRTN
• VREF circuit open
• Damaged PCM
• Open ACP circuit
• Damaged ACP sensor

Verify VREF voltage between 4.0 and 6.0V.

P1463 - Air Conditioning Pressure Sensor (ACP) Insufficient Pressure Change

Each time the A/C clutch engages, the PCM is looking for a pressure change in the refrigerant. If the change in pressure is outside of the calibration the DTC will set.

• A/C system mechanical failure
• Open ACP or VREF circuit
• A/C sensor damaged
• A/C system electrical failure
• A/C clutch always engaged

Verify A/C system function, including refrigerant charge.

P1464 - A/C Demand Out Of Self-Test Range

Indicates the ACCS input to the PCM was high during Self-Test.

• A/C was on during self-test
• A/C Clutch PWR circuit short to power (applications with N/C WAC relay contacts)
• ACCS circuit short to power
• Damaged A/C demand switch
• Damaged WAC relay (or CCRM)
• Damaged PCM

If A/C or defrost were on during self-test, turn off and rerun test.

P1469 - Low A/C Cycling Period

Indicates frequent A/C compressor clutch cycling.

• Mechanical A/C system concern (such as low refrigerant charge, damaged A/C cycling switch)
• Intermittent open between the cycling pressure switch and the PCM
• Intermittent open in IGN RUN circuit to cycling pressure switch (if applicable)

• An intermittent open circuit, although possible, is unlikely
• This test was designed to protect the transmission. In some strategies, the PCM will unlock the torque converter during A/C clutch engagement. If a concern is present that results in frequent A/C clutch cycling, damage could occur if the torque converter was cycled at these intervals. This test will detect this condition, set the DTC and prevent the torque converter from excessive cycling.

P1474 - Low Fan Control (LFC) Primary Circuit Failure
(applications with relay controlled electric cooling fan(s))

Monitors the low fan control (LFC) (fan control [FC] for one speed fan application) primary circuit output from the PCM. The test fails if: When the PCM grounds the LFC/FC circuit, excessive current draw is detected on the LFC/FC circuit; or with the LFC/FC circuit not grounded by the PCM, voltage is not detected on the LFC/FC circuit (the PCM expects to detect VPWR voltage coming through the low speed FC relay [or CCRM] coil to the LFC/FC circuit).

• Open or shorted LFC/FC circuit
• Open VPWR circuit to low speed FC relay
• Damaged low speed FC relay (or CCRM)
• Damaged PCM

• When the LFCF PID reads YES, a fault is currently present
• An open circuit or short to ground can only be detected when the PCM is not grounding the LFC/FC circuit
• A short to power can only be detected when the PCM is grounding the LFC/FC circuit.
• During KOEO and KOER Self-Test, the LFC/FC circuit will be cycled on and off

P1474 - Cooling Fan Electrical Malfunction
(applications with variable speed electric cooling fan)

This test checks the Fan Control - Variable (FCV) output circuit. The DTC sets if the PCM detects that the voltage on the FCV circuit is not within the expected range.

• FCV circuit open or shorted.
• B+ or ground circuit fault to cooling fan.
• Damaged cooling fan module.
• Damaged PCM.

During KOEO Self-Test, the cooling fan will be cycled on and off.

P1477 - Medium Fan Control (MFC) Primary Circuit Failure

Monitors the medium fan control (MFC) primary circuit output from the PCM. The test fails if: With the MFC output commanded on (grounded), excessive current draw is detected on the MFC circuit; or with the MFC circuit commanded off, voltage is not detected on the MFC circuit (the PCM expects to detect IGN START/RUN voltage coming through the medium speed FC relay coil to the MFC circuit).

• Open or shorted MFC circuit
• Open IGN START/RUN circuit to medium speed FC relay
• Damaged medium speed FC relay
• Damaged PCM

• Same as P1479, except with MFC circuit and MFCF PID (for early build Escape, MFCF and MFC PIDs may not be available)
• Using Output Test Mode on scan tool, when commanding the low speed fan on, the PCM will also activate the medium speed fan output.

P1479 - High Fan Control (HFC) Primary Circuit Failure

Monitors the high fan control (HFC) primary circuit output from the PCM. The test fails if: With the HFC output commanded on (grounded), excessive current draw is detected on the HFC circuit; or with the HFC circuit commanded off, voltage is not detected on the HFC circuit (the PCM expects to detect VPWR voltage coming through the high speed FC relay [or CCRM] coil to the HFC circuit).

• Open or shorted HFC circuit
• Open VPWR circuit to high speed FC relay
• Damaged high speed FC relay (or CCRM)
• Damaged PCM

• When the HFCF PID reads YES, a fault is currently present
• An open circuit or short to ground can only be detected when the PCM is not grounding the HFC circuit
• A short to power can only be detected when the PCM is grounding the HFC circuit
• During KOEO and KOER self-test, the HFC circuit will be cycled on and off

P1500 - Vehicle Speed Sensor (VSS) Intermittent

Indicates the VSS input signal was intermittent. This DTC is set when a VSS fault interferes with other OBDII tests, such as Catalyst efficiency monitor, EVAP monitor, HO2S monitor, etc.

• Intermittent VSS connections
• Intermittent open in VSS harness circuit(s)
• Intermittent short in VSS harness circuit(s)
• Damaged VSS
• Damaged PCM

P1501 - Vehicle Speed Sensor (VSS) Out of Self Test Range

Indicates the VSS input signal is out of Self Test range. If the PCM detects a VSS input signal any time during Self Test, a DTC P1501 will be set and the test will abort.

• Noisy VSS input signal from Radio Frequency Interference/ Electro-Magnetic Interference (RFI/EMI) external sources such as ignition wires, charging circuit or after market equipment.

Check for VSS input to be 0 mph when vehicle transmission is in Park.

P1502 - Vehicle Speed Sensor (VSS) Intermittent

Indicates the powertrain control module (PCM) detected an error in the vehicle speed information. Vehicle speed data is received from either the vehicle speed sensor (VSS), transfer case speed sensor (TCSS) or anti-lock brake system (ABS) control module. This DTC is set the same way as P0500. However, it is intended to flash the transmission control indicator lamp (TCIL) for first time VSS circuit error/malfunctions.

• Refer to possible causes for P0500.

Refer to diagnostic aids for P0500.

P1504 - Idle Air Control (IAC) Circuit Malfunction

This DTC is set when the PCM detects an electrical load failure on the IAC output circuit.

• IAC circuit open
• VPWR to IAC solenoid open
• IAC circuit short to PWR
• IAC circuit short to GND
• Damaged IAC valve
• Damaged PCM

• The IAC solenoid resistance is from 6 to 13 ohms.

P1506 - Idle Air Control (IAC) Overspeed Error

This DTC is set when the PCM detects engine idle speed that is greater than the desired rpm.

• IAC circuit short to GND
• Damaged IAC valve
• IAC valve stuck open
• Vacuum leaks
• Failed EVAP system
• Damaged PCM

Disconnect IAC valve and look for little or no change in engine rpm as an indication of a stuck or damaged valve.

P1507 - Idle Air Control (IAC) Underspeed Error

This DTC is set when the PCM detects engine idle speed that is less than the desired rpm.

• IAC circuit open
• IAC circuit short to PWR
• VPWR to IAC solenoid open
• Air inlet is plugged
• Damaged IAC solenoid
• Damaged PCM

• The IAC solenoid resistance is from 6 to 13 ohms
• Disconnect IAC valve and look for no change in engine rpm as an indication of a stuck or damaged valve

P1516 - Intake Manifold Runner Control Input Error (Bank 1)

P1517 - Intake Manifold Runner Control Input Error (Bank 2)

The IMRC system is monitored for failure during continuous or key ON engine OFF self-test. Each DTC will distinguish the corresponding failed bank for IMRC actuator assemblies with dual monitor switches. The test fails when the signal on the monitor pin is outside an expected calibrated range.

• Mechanical concern - bind, seize, damage or obstruction of IMRC hardware

• An IMRCM PID reading at closed throttle that is less than VREF may indicate a fault
• An IMRCM PID reading near 1 volt or greater with engine rpm of at least 3000 may indicate a fault

P1518 - Intake Manifold Runner Control Malfunction (Stuck Open)

The IMRC system is monitored for failure during continuous, key ON engine OFF or key ON engine running self-test. The test fails when the signal on the monitor pin is less than an expected calibrated range at closed throttle.

• IMRC monitor signal circuit shorted to PWR GND or SIG RTN
• Damaged IMRC actuator
• Damaged PCM

An IMRCM PID reading approximately near 1 volt at closed throttle may indicate a fault

P1519 - Inlet Manifold Runner Control Malfunction (Stuck Closed)

The IMRC system is monitored for failure during continuous, key ON engine OFF or key ON engine running self-test. The test fails when the signal on the monitor pin is more than an expected calibrated range with IMRC activated.

• IMRC monitor circuit open
• IMRC control circuit open
• IMRC monitor circuit short to VREF
• IMRC monitor return circuit open
• Damaged IMRC actuator
• IMRC VPWR circuit open
• Damaged PCM

An IMRCM PID reading at VREF with engine rpm of at least 3000 may indicate a fault.

P1549 - Intake Manifold Communication Control Circuit Malfunction

The IMCC or intake manifold tuning (IMT) valve system is monitored for failure during continuous or key ON engine OFF self-test. The test fails when the PCM detects a concern with IMT valve output circuit.

• Open IMT valve circuit
• Open VPWR circuit
• Shorted IMT valve circuit
• Damaged IMT valve
• Damaged PCM

• An IMT valve fault PID (IMTVF) displaying YES status may indicate a fault

P1550 - Power Steering Pressure (PSP) Sensor Malfunction

The PSP sensor input signal to PCM is continuously monitored. The test fails when the signal falls out of a maximum or minimum calibrated range.

• PSP sensor damaged
• Damaged PCM

• The DTC indicates the PSP sensor is out of Self-Test range.

P1572 - Brake Pedal Switch Circuit

Indicates that the brake input rationality test for brake pedal position (BPP) and brake pressure applied (BPA) switches has failed. One or both inputs to the PCM did not change state when it was expected to. Note: On vehicles with stability assist. BPP is connected to the ABS module and the ABS generates a Driver Brake Application (DBA) signal, which is than sent to the PCM.

• Misadjusted brake switches, BPP or BPA
• Blown fuse
• Damaged BPP switch
• Damaged BPA switch
• Open or short in BPP circuit
• Open or short in DBA circuit
• Open or short in BPA circuit
• Damaged PCM

DTC P1572 is set when the PCM does not see the proper sequence of the brake pedal input signal from both the BPP and BPA when the brake pedal is pressed and released.

P1582 - Electronic Throttle Monitor Data Available

Indicates actuation of restraint deployment, and Electronic Throttle Monitor data is available.

• The DTC only indicates the actuation of the restraint deployment system, do not replace the PCM because there is no fault indicated. Do not replace PCM.

P1633 - Keep Alive Power Voltage Too Low

Indicates that the Keep Alive Power (KAPWR) circuit has experienced a power interrupt.

• Open KAPWR circuit
• Intermittent KAPWR
• Damaged PCM

Loss of KAPWR to the PCM will result in a immediate MIL illumination and a P1633.

P1635 - Tire/Axle Ratio Out Of Acceptable Range

This Diagnostic Trouble Code (DTC) indicates the tire and axle information contained in Vehicle ID block (VID) does not match vehicle hardware.

• Incorrect tire size
• Incorrect axle ratio
• Incorrect VID configuration parameters

Using the scan tool, view the tire and axle parameters within the VID. They must match vehicle hardware.

P1636 - Inductive Signature Chip Communication Error

Indicates the PCM has lost communication with the Inductive Signature Chip.

• PCM damaged

P1639 - Vehicle ID Block Not Programed Or Is Corrupt

This diagnostic trouble code (DTC) indicates that the vehicle ID (VID) block is not programed or the information within is corrupt.

• New PCM
• Incorrect PCM
• Incorrect VID configuration

Using an enhanced scan tool, reprogram the PCM to the most recent calibration available.

P1640 - Powertrain DTC's Available in Another Module

Vehicles using a secondary Engine Control Module can request that the Powertrain Control Module illuminate the Check Engine Light when a failure occurs which affect emission.

• DTCs stored in a secondary module, which requested the MIL to be turned on.

Call-up PID address 0946 to determine secondary module requesting MIL illumination. Once secondary module is determined request DTCs from module.

P1650 - Power Steering Pressure (PSP) Switch Malfunction

In Key On, Engine Off Self-Test, this DTC indicates the PSP input to the PCM is high. In Key On, Engine Running Self-Test, this DTC indicates that the PSP input did not change state.

• Steering wheel must be turned during Key On, Engine Running Self-Test
• PSP switch/shorting bar damaged
• SIG RTN circuit open
• PSP circuit open or shorted to SIGRTN
• PCM damaged

P1651 - Power Steering Pressure (PSP) Switch Signal Malfunction

The PCM counts the number of times vehicle speed transitions from 0 to a calibratable speed. After a calibratable number of speed transitions the PCM expects that the PSP input should have changed. This DTC is set if the transition is not detected.

• Vehicle towed with engine running
• Power steering hydraulic concern was repaired but DTC was not erased
• PSP switch/shorting bar damaged
• SIG RTN circuit open
• PSP circuit open or shorted to SIGRTN
• PCM damaged

• Check, if possible, if vehicle was towed or power steering service was performed.
• Observe PSP V PID while checking wires for intermittents.

P1703 - Brake Switch Out of Self-Test Range

Indicates that during Key On Engine Off (KOEO) Self-Test, BPP signal was high. Or during Key On Engine Running (KOER) Self -Test, the BPP signal did not cycle high and low.

• Open or short in (BPP) circuit
• Open or short in stoplamp circuits
• Damaged PCM
• Malfunction in module(s) connected to BPP circuit (Rear Electronic Module [REM] Windstar, LS6/LS8 and Thunderbird or Lighting Control Module (LCM) for Town Car)
• Damaged Brake Switch
• Misadjusted Brake Switch

Check for proper function of stoplamps. Using scan tool, check BPP PID. Stoplamps and PID should toggle on and off with brake pedal activation.

P1705 - Transmission Range Sensor Out of Self-Test Range

Transmission Range circuit not indicating Park/Neutral during self-test.

• Gear selector not in Park/Neutral

Verify gear selector is in Park/Neutral.

P1709 - Park/Neutral Position Switch Out of Self-Test Range

The DTCs indicate that the voltage is high when it should be low.

• PNP/CPP circuit short to PWR
• Damaged PNP or CPP switch
• PNP/CPP circuit open in the SIGRTN
• Damaged PCM

When exercising either the PNP or CPP switch the voltage should cycle from 5.0V to low

P1780 - Transmission Control Switch Out of Self-Test Range

During KOER self-test the TCS has to be cycled, if not cycled a DTC is set.

• TCS circuit short or open
• Damaged TCS switch
• Damaged PCM

Verify the TCS switch cycles ON/OFF

P1900 - Output Shaft Speed sensor circuit intermittent failure

See DTC P0723

P2270 - Lack of HO2S-12 Switch, Sensor Indicates Lean

The downstream HO2S sensors are forced rich and lean and monitored by the PCM. The test fails if the PCM does not detect the output of the HO2S in a calibrated amount of time.

• Pinched, shorted, and corroded wiring and pins
• Crossed sensor wires
• Exhaust leaks
• Contaminated or damaged sensor

P2271 - Lack of HO2S-12 Switch, Sensor Indicates Rich

See DTC P2270

P2272 - Lack of HO2S-22 Switch, Sensor Indicates Lean

See DTC P2270

P2273 - Lack of HO2S-22 Switch, Sensor Indicates Rich

See DTC P2270