Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Aids
2004 Pontiac GTO StandardSECTION Diagnostic Aids
IMPORTANT:
- Before you service the PCM, remove any debris from the PCM connector surfaces. Inspect the PCM connector gaskets when you diagnose or replace the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent contaminant intrusion into the PCM.
- For any test that requires probing the PCM or component harness connectors, use the J 35616 Connector Test Adapter Kit. Using this kit prevents any damage to the harness connector terminals. Refer to Using Connector Test Adapters in Wiring Systems.
The PCM sets this DTC when the vehicle runs out of fuel. Inspect for the following conditions:
- The heated oxygen sensor (HO2S) wires-The sensor pigtail may be in contact with the exhaust manifold or the exhaust system.
- The oxygen supply-An oxygen supply inside the HO2S is necessary for proper operation. The HO2S wires provide the supply of oxygen. Inspect the HO2S wires and connections for breaks or for contamination. Refer to Heated Oxygen Sensor (HO2S) Wiring Repairs in Wiring Systems.
- An intermittent ground-Inspect for an intermittent ground in the signal wire between the connector and the sensor.
- Lean injectors-Perform the Injector Balance Test. Refer to Fuel Injector Balance Test with Tech 2 or Fuel Injector Balance Test with Special Tool .
- Fuel contamination-Water near the in-tank fuel pump inlet can be delivered to the injectors. Refer to Alcohol/Contaminants-in-Fuel Diagnosis (Without Special Tool) . The water causes a lean exhaust and can set a DTC.
- The fuel pressure-If the fuel pressure is too low, the system will be lean. Refer to Fuel System Diagnosis .
- Exhaust leaks-An exhaust leak near the HO2S can cause a lean condition. Refer to Exhaust Leakage in Engine Exhaust.
- Vacuum or crankcase leaks can cause a lean condition.
If the above components are OK, the HO2S may be at fault.
For an intermittent condition, refer to Symptoms - Engine Controls .
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.