626 1999-2001

2.5L V6 VIN - Auto 2

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Trouble Code: P0135



HO2S-11 (Bank 1 Sensor 1) Heater Circuit Malfunction

Possible Causes:



HO2S heater control circuit is open or shorted to ground
 
HO2S heater power circuit open between the heater and PCM
 
HO2S heater is damaged or has failed
 
PCM has failed (it controls the heater with a duty cycle signal)
 

Trouble Code: P0136



HO2S-12 (Bank 1 Sensor 2) No Activity Detected

Possible Causes:



Air leaks at the exhaust manifold or exhaust pipes
 
HO2S wiring crossed at the connector or shorted in the harness
 
HO2S signal circuit is open or shorted to ground
 
HO2S contaminated with wrong fuel, has deteriorated or failed
 

Trouble Code: P0137



HO2S-12 (Bank 1 Sensor 2) Lack of Switching (Too Lean)

Possible Causes:



HO2S signal circuit is open or shorted to ground
 
Air leaks at the exhaust manifold or exhaust pipes
 
HO2S contaminated with wrong fuel, has deteriorated or failed
 
PCM has failed
 

Trouble Code: P0138



HO2S-12 (Bank 1 Sensor 2) Lack of Switching (Too Rich)

Possible Causes:



HO2S signal tracking (wet/oily) in connector causing a short between the signal circuit and heater power circuit
 
HO2S signal circuit is shorted to system power
 
HO2S contaminated with wrong fuel, has deteriorated or failed
 
PCM has failed
 

Trouble Code: P0141



HO2S-21 (Bank 1 Sensor 1) Heater Circuit Malfunction

Possible Causes:



HO2S heater control circuit is open or shorted to ground
 
HO2S heater power circuit open between the heater and PCM
 
HO2S heater is damaged or has failed
 
PCM has failed (it controls the heater with a duty cycle signal)
 

Trouble Code: P0142



HO2S-13 (Bank 1 Sensor 3) Circuit Malfunction

Possible Causes:



Air leaks at the exhaust manifold or exhaust pipes
 
HO2S signal and grounded wire shorted inside the harness
 
HO2S contaminated due to wrong fuel, or it has deteriorated
 
PCM has failed
 

Trouble Code: P0142



HO2S-12 (Bank 1 Sensor 2) Circuit Malfunction

Possible Causes:



Air leaks at the exhaust manifold or exhaust pipes
 
HO2S contaminated due to wrong fuel, or it has deteriorated
 
PCM has failed
 

Trouble Code: P0147



HO2S-13 (Bank 1 Sensor 3) Heater Circuit Malfunction

Possible Causes:



HO2S heater control circuit is open or shorted to ground
 
HO2S heater power circuit open between the heater and PCM
 
HO2S heater is damaged or has failed
 
PCM has failed (it controls the heater with a duty cycle signal)
 

Trouble Code: P0147



HO2S-13 (Bank 1 Sensor 3) Heater Circuit Malfunction

Possible Causes:



HO2S heater control circuit is open or shorted to ground
 
HO2S heater control circuit is shorted to system power (B+)
 
HO2S heater power circuit open between the heater and PCM
 
HO2S heater is damaged or has failed
 
PCM has failed (it controls the heater with a duty cycle signal)
 

Trouble Code: P0153



HO2S-21 (Bank 2 Sensor 1) Circuit Slow Response

Possible Causes:



Air leaks in the intake manifold or exhaust manifold or pipes
 
IAT sensor or MAF sensor has deteriorated (out of calibration)
 
HO2S signal circuit is open or shorted to ground (intermittent)
 
HO2S contaminated with wrong fuel, has deteriorated or failed
 

Trouble Code: P0155



HO2S-21 (Bank 2 Sensor 1) Heater Circuit Malfunction

Possible Causes:



HO2S heater control circuit is open or shorted to ground
 
HO2S heater power circuit open between the heater and PCM
 
HO2S heater is damaged or has failed
 
PCM has failed (it controls the heater with a duty cycle signal)
 

Trouble Code: P0156



O2S 22-Circuit Malfunction

Possible Causes:



-Wiring concern
 
-Pinched, shorted, and corroded wiring and pins
 
-Crossed sensor wires
 
-Other concern
 
-Exhaust leaks
 
-Contaminated or damaged sensor
 

Trouble Code: P0161



O2S 22-Heater Circuit Malfunction

Possible Causes:



-O2S22 malfunction
 
-Open circuit between the main relay terminal E and O2S22 terminal C
 
-Open circuit between the O2S22 terminal E and PCM terminal 96
 
-Short to ground circuit between O2S22 terminal E and PCM terminal 96
 
-Short to power circuit between O2S22 terminal E and PCM terminal 96
 
-Poor connection at O2S22 or PCM connector
 
-PCM malfunction
 

Trouble Code: P0171



Adaptive Fuel Trim Too Lean (Bank 1)

Possible Causes:



Air leaks after the MAF sensor, or in the PCV or EGR system
 
Base engine -mechanical- fault affecting one or more cylinders
 
Exhaust leaks before or near where the front HO2S is mounted
 
Fuel control sensor out of calibration (i.e., ECT, IAT or MAF)
 
Fuel delivery system supplying too little fuel at idle or cruise
 
Fuel Injectors (one or more) is dirty, restricted or leaking fuel
 
HO2S is contaminated, deteriorated or it has failed
 
Vehicle driven low on fuel or driven until it ran out of fuel
 

Trouble Code: P0172



Fuel Trim System Too Rich

Possible Causes:



Fuel System
 
-Excessive fuel pressure
 
-Leaking fuel injector(s)
 
-Leaking pressure regulator
 
-Low fuel pressure or running out of fuel
 
-Contaminated fuel injector(s)
 
Base Engine
 
-Oil overfill
 
-Cam timing
 
-Cylinder compression
 
-Exhaust leaks before or near HO2S
 
Induction System
 
-Air leaks between the MAF sensor and intake manifold
 
-Vacuum leaks
 
-Restricted air inlet
 
-Positive crankcase ventilation (PCV) system
 
-Fuel purge system
 
-Improperly seated engine oil dipstick
 
EGR System
 
-Leaking gasket
 
-Stuck open EGR valve
 
-Leaking diaphragm
 

Trouble Code: P0174



Adaptive Fuel Trim Too Lean (Bank 1)

Possible Causes:



Air leaks after the MAF sensor, or in the PCV or EGR system
 
Base engine -mechanical- fault affecting one or more cylinders
 
Exhaust leaks before or near where the front HO2S is mounted
 
Fuel control sensor out of calibration (i.e., ECT, IAT or MAF)
 
Fuel delivery system supplying too little fuel at idle or cruise
 
Fuel Injectors (one or more) is dirty, restricted or leaking fuel
 
HO2S is contaminated, deteriorated or it has failed
 
Vehicle driven low on fuel or driven until it ran out of fuel
 

Trouble Code: P0175



Adaptive Fuel Trim Too Rich (Bank 2)

Possible Causes:



One or more injectors leaking or pressure regulator is leaking
 
Fuel delivery system supplying too much fuel during cruise or idle periods (e.g., faulty fuel pump, or faulty pressure regulator)
 
Exhaust leaks before or near where the front HO2S is mounted
 
HO2S is contaminated, deteriorated or it has failed
 
EVAP system component has failed or canister fuel saturated
 
Fuel control sensor is out of calibration (i.e., ECT, IAT or MAP)
 
Base engine -mechanical- fault affecting one or more cylinders
 

Trouble Code: P0230



Fuel Pump Primary Circuit Malfunction

Possible Causes:



Fuel pump primary circuit is open or shorted to ground
 
Fuel pump primary circuit is shorted to system power (VREF)
 
Fuel pump relay is damaged or has failed
 
PCM has failed
 

Trouble Code: P0300



Random Misfire Detected

Possible Causes:



Base engine mechanical fault affecting one or more cylinders
 
CMP sensor is damaged or failed (problem may be intermittent)
 
Fuel metering fault that affects more than one cylinder
 
Fuel pressure too low or too high, fuel supply contaminated
 
EVAP system problem or the EVAP canister is fuel saturated
 
EGR valve is stuck open or the PCV system has a vacuum leak
 
Ignition system fault that affects more than one cylinder
 
MAF sensor is contaminated (this can cause a lean condition)
 

Trouble Code: P0301



Cylinder 1 Misfire Detected

Possible Causes:



Base engine mechanical fault affecting only Cylinder 1
 
CKP sensor is damaged or failed (problem may be intermittent)
 
Fuel metering fault that affects only Cylinder 1
 
Ignition system fault that affects only Cylinder 1
 

Trouble Code: P0302



Cylinder 2 Misfire Detected

Possible Causes:



Base engine mechanical fault affecting only Cylinder 2
 
CKP sensor is damaged or failed (problem may be intermittent)
 
Fuel metering fault that affects only Cylinder 2
 
Ignition system fault that affects only Cylinder 2
 

Trouble Code: P0303



Cylinder 3 Misfire Detected

Possible Causes:



Base engine mechanical fault affecting only Cylinder 3
 
CKP sensor is damaged or failed (problem may be intermittent)
 
Fuel metering fault that affects only Cylinder 3
 
Ignition system fault that affects only Cylinder 3
 

Trouble Code: P0304



Cylinder 4 Misfire Detected

Possible Causes:



Base engine mechanical fault affecting only Cylinder 4
 
CKP sensor is damaged or failed (problem may be intermittent)
 
Fuel metering fault that affects only Cylinder 4
 
Ignition system fault that affects only Cylinder 4
 

Trouble Code: P0305



Cylinder 5 Misfire Detected

Possible Causes:



Base engine mechanical fault affecting only Cylinder 5
 
CKP sensor is damaged or failed (problem may be intermittent)
 
Fuel metering fault that affects only Cylinder 5
 
Ignition system fault that affects only Cylinder 5
 

Trouble Code: P0306



Cylinder 6 Misfire Detected

Possible Causes:



Base engine mechanical fault affecting only Cylinder 6
 
CKP sensor is damaged or failed (problem may be intermittent)
 
Fuel metering fault that affects only Cylinder 6
 
Ignition system fault that affects only Cylinder 6
 

Trouble Code: P0320



Ignition Engine Speed (PIP) Signal Error

Possible Causes:



Engine speed or PIP signal circuit is open (an intermittent fault)
 
Engine speed signal circuit shorted to ground (intermittent)
 
Ignition system components arcing (ignition coils or wires)
 
Vehicle onboard transmitter interruption (i.e., 2-way radio)
 

Trouble Code: P0325



Knock Sensor Circuit Malfunction

Possible Causes:



Knock sensor signal circuit is open
 
Knock sensor signal circuit is shorted to ground
 
Knock sensor is damaged or has failed
 
PCM is damaged
 

Trouble Code: P0340



Camshaft Position Sensor Circuit Malfunction

Possible Causes:



CMP sensor signal is open or shorted to ground
 
CMP sensor signal is shorted to VREF or system power (B+)
 
CMP sensor is damaged or has failed
 
CMP sensor shielding may be open or damaged
 
PCM has failed
 

Trouble Code: P0400



EGR System Flow Malfunction

Possible Causes:



EGR boost solenoid control circuit is open or shorted to ground
 
EGR boost solenoid power circuit is open to the Main Relay
 
EGR boost solenoid is damaged or has failed
 
EGR boost sensor is damaged or has failed
 
EGR valve assembly is leaking, damaged or has failed
 
EGR valve vacuum hose(s) lose, damaged or disconnected
 
MAF sensor or TP sensor has drifted out-of-calibration
 
Exhaust pipe to EGR boost sensor or solenoid leaking/plugged
 
PCM has failed
 

Trouble Code: P0420



Catalyst Efficiency Below Normal (Bank 1)

Possible Causes:



Air leaks at the exhaust manifold or in the exhaust pipes
 
Catalytic converter is contaminated, damaged or has failed
 
Front HO2S and/or the rear HO2S is loose in the mounting hole
 
Front HO2S older (aged) than the rear HO2S (HO2S is lazy)
 
Front HO2S or rear HO2S is contaminated with fuel or moisture
 

Trouble Code: P0421



Catalyst Efficiency Below Normal (Bank 1)

Possible Causes:



Air leaks at the exhaust manifold or in the exhaust pipes
 
Catalytic converter is contaminated, damaged or has failed
 
Front HO2S and/or the rear HO2S is loose in the mounting hole
 
Front HO2S older (aged) than the rear HO2S (HO2S is lazy)
 
Front HO2S or rear HO2S is contaminated with fuel or moisture
 

Trouble Code: P0430



Catalyst Efficiency Below Normal (Bank 2)

Possible Causes:



Air leaks at the exhaust manifold or in the exhaust pipes
 
Catalytic converter is contaminated, damaged or has failed
 
Front HO2S and/or the rear HO2S is loose in the mounting hole
 
Front HO2S older (aged) than the rear HO2S (HO2S is lazy)
 
Front HO2S or rear HO2S is contaminated with fuel or moisture
 

Trouble Code: P0431



Warm-up Catalyst Efficiency Below Normal (Bank 2)

Possible Causes:



Air leaks at the exhaust manifold or in the exhaust pipes
 
Catalytic converter is contaminated, damaged or has failed
 
Front HO2S and/or the rear HO2S is loose in the mounting hole
 
Front HO2S older (aged) than the rear HO2S (HO2S is lazy)
 
Front HO2S or rear HO2S is contaminated with fuel or moisture
 

Trouble Code: P0442



EVAP System Small Leak (0.040-) Detected

Possible Causes:



Fuel filler cap loose, cross-threaded, incorrect part or damaged
 
Purge solenoid valve is damaged or has failed
 
Charcoal canister is loaded with fuel or moisture
 
Tank pressure control valve (TPCV) is damaged or has failed
 
Canister drain cut valve (CDCV) is damaged or has failed
 
Rollover valve or catch tank valve is damaged or leaking
 
Fuel tank is cracked (leaking), or a leak exists in the tank seal
 
Fuel tank pressure sensor is damaged or has failed
 
ECT, IAT, MAF, VSS or TP sensor signals out-of-calibration
 
Vapor line(s) damaged or leaking between the purge solenoid and the intake manifold, EVAP purge solenoid valve and the canister, canister drain cut valve and the rollover valve
 
PCM has failed
 

Trouble Code: P0443



EVAP Canister Purge Solenoid Circuit Malfunction

Possible Causes:



Purge solenoid control circuit is open or shorted to ground
 
Purge solenoid control circuit is shorted to system power (B+)
 
Purge solenoid power circuit is open or shorted to ground
 
Purge solenoid is damaged or has failed
 
PCM has failed (the purge solenoid driver may be damaged)
 

Trouble Code: P0446



EVAP System Vent Control Malfunction

Possible Causes:



CDCV is damaged, sticking or has failed
 
Canister Vent side filter is damaged or missing
 
Charcoal canister is loaded with fuel or moisture
 
FTP sensor signal circuit is open, shorted to ground or to power
 
FTP sensor power circuit is open or shorted to ground
 
FTP sensor is damaged or has failed
 
BARO, ECT, IAT, MAF, VSS or TP sensor is out-of-calibration
 
Fuel tank level sensor is damaged or out-of-calibration
 
Fuel vapor storage canister vent is plugged or restricted
 
Fuel vapor line(s) kinked or blocked between the CDVC solenoid and the intake manifold
 

Trouble Code: P0446



Evaporative Emission Control System (Vent Control Malfunction)

Possible Causes:



-Damaged FTP sensor
 
-Kinks or blockage in fuel vapor hose/tube
 
-Constant voltage circuit to FTP sensor open
 
-Fuel vapor storage canister vent restriction
 
-Damaged Canister Vent side filter
 
-Damaged Canister Drain Cut Valve (CDCV)
 
-Damaged PCM
 

Trouble Code: P0452



EVAP Pressure Sensor Circuit Low Input

Possible Causes:



FTP sensor is completely submerged in fuel inside the fuel tank
 
FTP sensor signal circuit is shorted to sensor ground
 
FTP sensor signal circuit is shorted to chassis ground
 
FTP sensor is damaged or has failed
 
PCM has failed
 

Trouble Code: P0453



EVAP Pressure Sensor Circuit High Input

Possible Causes:



FTP sensor signal circuit is shorted to VREF or power (B+)
 
FTP sensor ground circuit is open
 
FTP sensor is damaged or has failed
 
PCM has failed
 

Trouble Code: P0455



EVAP System Large Leak (0.080-) Detected

Possible Causes:



Fuel filler cap loose, cross-threaded, incorrect part or damaged
 
Charcoal canister is loaded with fuel or moisture, or has failed
 
Canister drain cut valve (CDCV) is damaged or leaking
 
Fuel tank pressure (FTP) sensor is damaged or has failed
 
Fuel level sensor is damaged or out-of-calibration
 
Purge solenoid valve is damaged or has failed
 
Vent cut valve is damaged, is leaking or has failed
 
IAT, ECT, MAF, MAP, VSS or TP sensor is out-of-calibration
 
Catch tank or rollover valve is damaged, or fuel tank is leaking
 
Vapor line(s) damaged or leaking between the purge solenoid and intake manifold, purge solenoid and canister, or between the CDCV and vent cut valve, check valve and rollover valve
 
PCM has failed
 

 
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