Diagnostic Aids

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

NOTE: Remove any debris from the PCM connector surfaces before servicing the PCM. 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.

This diagnostic only runs once per ignition cycle.
A malfunction in the HO2S heater circuits causes a DTC to set. Check the HO2S heater circuits for intermittent opens and for poor connections.
An oxygen supply inside the HO2S is necessary for proper operation. The HO2S wires provide the supply of oxygen. Inspect the HO2S wires and the connections for breaks or for contamination.
Using the Freeze Frame/Failure Records may help to locate an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame/Failure Records can help to determine how many miles since the DTC set. The Fail Counter and the Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass or a fail. In order to isolate when the DTC failed, operate the vehicle within the same Freeze Frame conditions. These conditions include:
- The RPM
- The vehicle load
- The vehicle speed
- The temperature