Diagnostic Aids
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2003 GMC Yukon XL, 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Suburban, and 2003 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- The catalyst test may abort due to a change in the engine load. DO NOT change the engine load during the test. During the test, DO NOT reset the AC, Coolant Fan, or the Heater Motor.
- Inspect the fuel control oxygen sensor wiring harness for a short to the catalysts monitor wiring harness.
- Driving the vehicle under the conditions outlined in DRIVE CYCLES can verify whether the fault is present.
- Certain conditions may cause a catalytic converter to degrade. These conditions may include the following:
- An engine misfire, which can cause catalytic convertor overheating.
- High engine oil high coolant consumption.
- Retarded spark timing.
- A conditions that may cause low secondary ignition voltage, which can cause incomplete combustion.
- A lean fuel mixture.
- A rich fuel mixture.
- A shorted oxygen sensor wiring harness.
- Correct any condition that may cause an engine performance concern.
- If an intermittent condition cannot be duplicated, the information included in the Freeze Frame/Failure Records can be useful in determining the vehicle operating conditions when the DTC was set.