Diagnostic Aids

WARNING: This page is about a different car, the 2001 GMC Savana, 2001 Chevrolet RV Cutaway, 2001 Chevrolet Cutaway, and 2001 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.

This diagnostic only runs once per ignition cycle.
A malfunction in HO2S heater circuits causes a DTC to set. Check HO2S heater circuits for intermittent opens and for poor connections.
An oxygen supply inside HO2S is necessary for proper operation. HO2S wires provide supply of oxygen. Inspect HO2S wires and connections for breaks or for contamination.
Using FREEZE FRAME/FAILURE RECORDS may help to locate an intermittent condition. If you cannot duplicate DTC, information included in FREEZE FRAME/FAILURE RECORDS can help to determine how many miles since DTC set. Fail Counter and Pass Counter can also help determine how many ignition cycles diagnostic reported a pass or a fail. To isolate when DTC failed, operate vehicle within freeze frame conditions.