Possible causes – Engine Control Module (ECM) Harness power supply circuit is open or shorted– Engine Control Module (ECM) Programming– Faulty Engine Control Module (ECM) Tech notes Check the PCM fuse, if fuse is OK try erasing the code first

Possible causes – Engine mechanical problems– Incorrect timing chain– Stretched timing chain– Failed camshaft actuator or actuator solenoid Tech notes There is a factory service bulletin for the following Buick models: 2004-2006 Buick Rendezvous2005-2008 Buick Lacrosse2008 Buick Enclave The service

Possible causes – Engine mechanical problems– Incorrect timing chain– Stretched timing chain– Failed camshaft actuator or actuator solenoid Tech notes There is a factory service bulletin for the following Buick models: 2004-2006 Buick Rendezvous2005-2008 Buick Lacrosse2008 Buick Enclave The service

Possible causes – Faulty Air Pump inoperative– Air bypass solenoid harness is open or shorted– Air bypass solenoid circuit poor electrical connection When is the code detected? If the fault detection circuit senses a voltage other than what is expected,

Possible causes – Faulty Air Pump inoperative– Air bypass solenoid harness is open or shorted– Air bypass solenoid circuit poor electrical connection When is the code detected? If the fault detection circuit senses a voltage other than what the Powertrain

Possible causes – Faulty Brake Switch– Brake Switch harness is open or shorted– Brake Switch circuit poor electrical connection When is the code detected? When the Powertrain Control Module (PCM) detects an open brake switch circuit (0 volts, low input)

Possible causes – Faulty Brake Switch– Brake Switch harness is open or shorted– Brake Switch circuit poor electrical connection– Misadjusted Brake Switch When is the code detected? The stop light switch does not turn off even once vehicle is driven.

Possible causes – Faulty Camshaft Position Sensor– Camshaft Position Sensor harness is open or shorted– Camshaft Position Sensor circuit poor electrical connection– Faulty starter motor– Starting system circuit– Dead (Weak) battery Tech notes On some Buick models the camshaft position

Possible causes – Faulty Camshaft Position Sensor– Camshaft Position Sensor harness is open or shorted– Camshaft Position Sensor circuit poor electrical connection– Faulty starter motor– Starting system circuit– Dead (Weak) battery Tech notes On some Buick models the camshaft position

Possible causes – Faulty Camshaft Position Sensor– Camshaft Position Sensor harness is open or shorted– Camshaft Position Sensor circuit poor electrical connection– Faulty starter motor– Starting system circuit– Dead (Weak) battery Tech notes Sometimes and in some models, low battery

Possible causes – Faulty Camshaft Position Sensor– Camshaft Position Sensor harness is open or shorted– Camshaft Position Sensor circuit poor electrical connection– Faulty starter motor– Starting system circuit– Dead (Weak) battery Tech notes Sometimes and in some models, low battery

Possible causes – Faulty Clutch Switch– Misadjusted Clutch Switch– Clutch Switch harness is open or shorted– Clutch Switch circuit poor electrical connection– Faulty Engine Control Module (ECM) Tech notes Check clutch switch adjustment, the switch should open and close when

Possible causes – Faulty crankshaft position sensor– Crankshaft position sensor harness is open or shorted– Crankshaft position sensor circuit poor electrical connection When is the code detected? The Powertrain Control Module (PCM) determines no signal from the Crankshaft Position (CKP)

Possible causes – Faulty crankshaft position sensor– Crankshaft position sensor harness is open or shorted– Crankshaft position sensor circuit poor electrical connection– Signal plate may be damage– Starter motor may be faulty– Starting system circuit– Dead or weak battery When

Possible causes – Faulty EGR volume control solenoid valve– EGR volume control solenoid valve harness is open or shorted– EGR volume control solenoid valve circuit poor electrical connection– EGR temperature sensor and circuit When is the code detected? An improper

Possible causes – Faulty Engine Control Module (ECM)– ECM harness is open or shorted– ECM circuit poor electrical connection– Shorted sensor on 5 volt circuit When is the code detected? The Engine Control Module (ECM) has detected the sensor 5

Possible causes – Faulty EVAP canister vent valve– Faulty EVAP canister pruge valve– Plugged EVAP canister condition– Faulty EVAP pressure sensor When is the code detected? The ECM has detected pressure in the EVAP system during a non-purge condition. P0496

Possible causes – Faulty Evaporative Emission (EVAP) Purge Solenoid Control– Evaporative Emission (EVAP) Purge Solenoid Control harness is open or shorted– Evaporative Emission (EVAP) Purge Solenoid Control circuit poor electrical connection When is the code detected? The Powertrain Control Module

Possible causes – Faulty fan control relay– Fan control relay harness is open or shorted– Fan control relay circuit poor electrical connection– Faulty cooling fan 1– Fan cooling fan harness is open or shorted– Fan cooling fan circuit poor electrical

Possible causes – Faulty fan control relay– Faulty cooling fan 2– Fan control relay harness is open or shorted– Fan control relay circuit poor electrical connection– Fan cooling fan harness is open or shorted– Fan cooling fan circuit poor electrical