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.

Use FREEZE FRAME/FAILURE RECORDS to help locate an intermittent condition. If you cannot duplicate DTC, information in FREEZE FRAME/FAILURE RECORDS can help to determine how many miles have occurred 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 same freeze frame conditions such as RPM, load, vehicle speed, temperature, etc. that you observed.
Heater diagnostic will only run on a cold start and run once per ignition cycle.
An oxygen supply inside HO2S is necessary for proper operation. HO2S wires provide supply of oxygen. Inspect HO2S wires and inspect connections for breaks or for contamination.

Fig 1: Identifying Heated Oxygen Sensor 2 Connector Terminals

Courtesy of GENERAL MOTORS CORP.