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 Buick 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

Possible causes – Faulty fuel composition sensor– Fuel Composition Sensor harness is open or shorted– Fuel Composition Sensor circuit poor electrical connection Tech notes Replaced Fuel Composition Sensor When is the code detected? The ECM detects that the fuel composition

Possible causes – Faulty fuel injector 1– Fuel Injector 1 harness is open or shorted– Fuel injector 1 circuit poor electrical connection When is the code detected? If an electrical malfunction occurs in the fuel injector circuit for engine cylinder

Possible causes – Faulty fuel injector 2– Fuel Injector 2 harness is open or shorted– Fuel injector 2 circuit poor electrical connection When is the code detected? If an electrical malfunction occurs in the fuel injector circuit for engine cylinder

Possible causes – Faulty fuel injector 3– Fuel Injector 3 harness is open or shorted– Fuel injector 3 circuit poor electrical connection When is the code detected? If an electrical malfunction occurs in the fuel injector circuit for engine cylinder

Possible causes – Faulty fuel injector 4– Fuel Injector 4 harness is open or shorted– Fuel injector 4 circuit poor electrical connection When is the code detected? If an electrical malfunction occurs in the fuel injector circuit for engine cylinder

Possible causes – Faulty fuel injector 5– Fuel Injector 5 harness is open or shorted– Fuel injector 5 circuit poor electrical connection When is the code detected? If an electrical malfunction occurs in the fuel injector circuit for engine cylinder

Possible causes – Faulty fuel injector 6– Fuel Injector 6 harness is open or shorted– Fuel injector 6 circuit poor electrical connection When is the code detected? If an electrical malfunction occurs in the fuel injector circuit for engine cylinder

Possible causes – Faulty fuel injector 7– Fuel Injector 7 harness is open or shorted– Fuel injector 7 circuit poor electrical connection When is the code detected? If an electrical malfunction occurs in the fuel injector circuit for engine cylinder

Possible causes – Faulty fuel injector 8– Fuel Injector 8 harness is open or shorted– Fuel injector 8 circuit poor electrical connection When is the code detected? If an electrical malfunction occurs in the fuel injector circuit for engine cylinder