Diagnostic Aids

WARNING: This page is about a different car, the 2002 GMC Sierra and 2002 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Before you service the PCM, remove any debris from the PCM connector surfaces. Inspect the PCM connector gaskets when diagnosing or replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

An oxygen supply inside the HO2S is necessary for proper operation. The HO2S wires provides the supply of oxygen. Inspect the HO2S wires and connections for breaks or contamination.
For an intermittent condition, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.