Possible causes – Faulty cylinder #7 glow plug– Cylinder #7 glow plug harness is open or shroted– Cylinder #7 glow plug circuit poor electrical connection– Faulty glow plug module When is the code detected? The Engine Control Module (ECM) has

Possible causes – Faulty cylinder #8 glow plug– Cylinder #8 glow plug harness is open or shroted– Cylinder #8 glow plug circuit poor electrical connection– Faulty glow plug module When is the code detected? The Engine Control Module (ECM) has

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 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

Possible causes – Faulty Front Heated Oxygen Sensor (HO2S) Bank 1– Front Heated Oxygen Sensor (HO2S) Bank 1 harness is open or shorted– Front Heated Oxygen Sensor (HO2S) Bank 1 circuit poor electrical connection– Inappropriate fuel pressure– Faulty fuel injectors–

Possible causes – Faulty Front Heated Oxygen Sensor Bank 1– Front Heated Oxygen Sensor Bank 1 harness is open or shorted– Front Heated Oxygen Sensor Bank 1 circuit poor electrical connection– Inappropriate fuel pressure– Faulty fuel injectors– Intake air leaks

Possible causes – Faulty Front Heated Oxygen Sensor Bank 1– Front Heated Oxygen Sensor Bank 1 harness is open or shorted– Front Heated Oxygen Sensor Bank 1 circuit poor electrical connection– Inappropriate fuel pressure– Faulty fuel injectors– Intake air leaks

Possible causes – Faulty Front Heated Oxygen Sensor Bank 1– Front Heated Oxygen Sensor Bank 1 harness is open or shorted– Front Heated Oxygen Sensor Bank 1 circuit poor electrical connection– Inappropriate fuel pressure– Faulty fuel injectors– Intake air leaks

Possible causes – Faulty Front Heated Oxygen Sensor Bank 1– Front Heated Oxygen Sensor Bank 1 harness is open or shorted– Front Heated Oxygen Sensor Bank 1 circuit poor electrical connection– Inappropriate fuel pressure– Faulty fuel injectors– Intake air leaks

Possible causes – Faulty Front Heated Oxygen Sensor Bank 2– Front Heated Oxygen Sensor Bank 2 harness is open or shorted– Front Heated Oxygen Sensor Bank 2 circuit poor electrical connection– Inappropriate fuel pressure– Faulty fuel injectors– Intake air leaks

Possible causes – Faulty Front Heated Oxygen Sensor Bank 2– Front Heated Oxygen Sensor Bank 2 harness is open or shorted– Front Heated Oxygen Sensor Bank 2 circuit poor electrical connection– Inappropriate fuel pressure– Faulty fuel injectors– Intake air leaks

Possible causes – Faulty Front Heated Oxygen Sensor Bank 2– Front Heated Oxygen Sensor Bank 2 harness is open or shorted– Front Heated Oxygen Sensor Bank 2 circuit poor electrical connection– Inappropriate fuel pressure– Faulty fuel injectors– Intake air leaks–

Possible causes – Faulty Front Heated Oxygen Sensor Bank 2– Intake air leaks may be faulty– Exhaust gas leaks– Front Heated Oxygen Sensor Bank 2 harness is open or shorted– Front Heated Oxygen Sensor Bank 2 circuit poor electrical connection–

Possible causes – Faulty front heated oxygen sensor– Ignition misfiring– Faulty fuel injectors– Exhaust gas leaks– Incorrect fuel pressure – Faulty Mass Air Flow (MAF) sensor Tech notes There is a factory service bulletin for the following GMC models: 2000-2008

Possible causes – Faulty front heated oxygen sensor– Ignition misfiring– Faulty fuel injectors– Exhaust gas leaks– Incorrect fuel pressure– Faulty Mass Air Flow (MAF) sensor When is the code detected? – Fuel injection system does not operate properly– The amount