OBD II Code List

Possible causes

• 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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

• VREF voltage should be between 4.0 and 6.0 volts

• PID reading is in frequency

Possible causes

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

Diagnostic notes

• VREF should be greater than 4.0 volts

• PID reading is in frequency/volts

Possible causes

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

Diagnostic notes

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

Possible causes

• Loose electrical connection
• Damaged BARO sensor

Diagnostic notes

Check harness and connection.

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

• 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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

• 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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

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

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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

Possible causes

• 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.

Diagnostic notes

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

Possible causes

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

Possible causes

• See possible causes for P0132.

Diagnostic notes

See diagnostic aids for P0132.

Possible causes

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

Possible causes

• See possible causes for P0132.

Diagnostic notes

See diagnostic aids for P0132.

Possible causes

• See possible causes for P0132.

Diagnostic notes

See diagnostic aids for P0132.

Possible causes

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).

Diagnostic notes

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

Possible causes

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.

Diagnostic notes

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

Possible causes

See Possible Causes for P0171.

Diagnostic notes

See Diagnostic Aides for P0171

Possible causes

See Possible Causes for P0172.

Diagnostic notes

See Diagnostic Aides for P0172

Possible causes

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

Diagnostic notes

Verify EFT-PID value to determine open or short.

Possible causes

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

Diagnostic notes

Verify EFT-PID value to determine open or short.

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

Verify EFT-PID value to determine open or short.

Possible causes

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

Diagnostic notes

Verify VREF voltage between 4.0 and 6.0V.

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

• 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.

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

• Faulty fuel injector driver within the PCM.

Diagnostic notes

PID Data Monitor INJ1F-INJ12F fault flags = YES.

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

• 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)

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

• 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.

Possible causes

• 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.

Diagnostic notes

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

Possible causes

• 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

Diagnostic notes

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).

Possible causes

• 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

Diagnostic notes

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

Possible causes

• 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

Diagnostic notes

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.

Possible causes

• Vehicle driven at a high rate of speed

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

• Damaged Crankshaft Pulse Wheel teeth.
• Damaged CKP sensor

Diagnostic notes

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)

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

The DTC indicates that two successive erratic PIP pulses occurred.

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

• 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

Diagnostic notes

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

Possible causes

• 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

Diagnostic notes

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

Possible causes

• 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

Possible causes

• 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

Possible causes

• 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

Diagnostic notes

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.

Possible causes

• 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

Diagnostic notes

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.

Possible causes

• 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

Diagnostic notes

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.

Possible causes

• 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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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.

Possible causes

• 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

Diagnostic notes

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.

Possible causes

• 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

Diagnostic notes

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.

Possible causes

• 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)

Possible causes

• 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

Diagnostic notes

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.

Possible causes

• 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

Diagnostic notes

• 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

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

• 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

Diagnostic notes

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

Possible causes

• 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).

Possible causes

• 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.

Diagnostic notes

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.

Possible causes

• 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

Diagnostic notes

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.

Possible causes

• 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

Diagnostic notes

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.

Possible causes

• 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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

• 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

Possible causes

• 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.

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

• 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

Possible causes

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

Diagnostic notes

• 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.

Possible causes

• 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.

Diagnostic notes

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.

Possible causes

• Refer to possible causes for P0500.

Diagnostic notes

Refer to diagnostic aids for P0500.

Possible causes

• 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.

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

• 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)

Diagnostic notes

• 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.

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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).

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

• VID data corrupted by the scan tool during VID reprogramming

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

• Damaged PCM

Possible causes

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

Possible causes

• 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.

Diagnostic notes

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

Possible causes

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

Diagnostic notes

• 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

Possible causes

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

Diagnostic notes

An IMTVM PID reading may indicate a fault if available

Possible causes

• 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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

Verify sensor signal output varies with vehicle speed.

Possible causes

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

Diagnostic notes

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

Possible causes

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

Possible causes

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

Diagnostic notes

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

Possible causes

• 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

Diagnostic notes

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

Possible causes

• 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

Diagnostic notes

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.

Possible causes

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

Possible causes

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

Diagnostic notes

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.

Possible causes

• 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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

• 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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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

Possible causes

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

Possible causes

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

Possible causes

• 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)

Diagnostic notes

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

Possible causes

See Possible Causes for P1130

Possible causes

See Possible Causes for P1130

Possible causes

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

Possible causes

See Possible Causes for P1130

Possible causes

See Possible Causes for P1130

Possible causes

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

Diagnostic notes

• 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

Possible causes

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

Possible causes

• Restriction in the fuel line
• Plugged fuel filter

Possible causes

• Fuel pressure regulator

Possible causes

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

Diagnostic notes

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

Possible causes

• 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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

• 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.

Possible causes

• 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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

• 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.

Possible causes

• 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

Diagnostic notes

• 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.

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

• Previous theft condition
• Anti-Theft System failure

Diagnostic notes

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.

Possible causes

• 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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

• 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)

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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

Possible causes

• 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)

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

• 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)

Possible causes

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

Diagnostic notes

• 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)

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

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).

Possible causes

• 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).

Diagnostic notes

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.

Possible causes

• 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

Possible causes

• 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

Diagnostic notes

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.

Possible causes

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

Diagnostic notes

• 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

Possible causes

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

Diagnostic notes

Verify VREF voltage between 4.0 and 6.0V.

Possible causes

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

Diagnostic notes

Verify VREF voltage between 4.0 and 6.0V.

Possible causes

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

Diagnostic notes

Verify A/C system function, including refrigerant charge.

Possible causes

• 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

Diagnostic notes

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

Possible causes

• 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)

Diagnostic notes

• 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.

Possible causes

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

Diagnostic notes

• 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

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

• 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.

Possible causes

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

Diagnostic notes

• 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

Possible causes

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

Possible causes

• 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.

Diagnostic notes

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

Possible causes

• Refer to possible causes for P0500.

Diagnostic notes

Refer to diagnostic aids for P0500.

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

• 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

Possible causes

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

Diagnostic notes

• 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

Possible causes

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

Diagnostic notes

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

Possible causes

• 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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

• PSP sensor damaged
• Damaged PCM

Diagnostic notes

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

Possible causes

• 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

Diagnostic notes

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.

Possible causes

• 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.

Possible causes

• Open KAPWR circuit
• Intermittent KAPWR
• Damaged PCM

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

• PCM damaged

Possible causes

• New PCM
• Incorrect PCM
• Incorrect VID configuration

Diagnostic notes

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

Possible causes

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

Diagnostic notes

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

Possible causes

• 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

Possible causes

• 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

Diagnostic notes

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

Possible causes

• 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

Diagnostic notes

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

Possible causes

• Gear selector not in Park/Neutral

Diagnostic notes

Verify gear selector is in Park/Neutral.

Possible causes

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

Diagnostic notes

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

Possible causes

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

Diagnostic notes

Verify the TCS switch cycles ON/OFF

Possible causes

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