Diagnostic Procedures
WARNING: This page is about a different car, the 2002 Pontiac Sunfire, 2002 Pontiac Grand Am, 2002 Oldsmobile Alero, and 2002 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
- Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
- Operate the engine at normal operating temperature. Operate the engine at greater than 1200 RPM for two minutes. With a scan tool, observe the HO2S 1 voltage parameter. Does the scan tool indicate that the HO2S 1 voltage is varying at greater than and less than the specified values of 350-550 millivolts? If yes, go to next step. If no, go to step 4.
- Observe the Freeze Frame/Failure Records data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running the DTC or as close to the Freeze Frame/Failure Records data that you observed. See CONDITIONS FOR RUNNING DTC . Does the scan tool indicate that this DTC failed this ignition? If yes, go to next step. If no, go to INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.
- Turn ignition off. Disconnect HO2S 1. Turn ignition on, with engine off. Using a Digital Multimeter (DMM), measure the voltage of the HO2S 1 high signal circuit on the PCM side to a good ground. Does the voltage measure within 350-550 millivolts? If yes, go to next step. If no, go to step 9.
- Turn ignition off. Connect a 3-amp fused jumper wire between the HO2S 1 harness connector high signal circuit and low signal circuit. Turn ignition on. Use scan tool in order to monitor HO2S 1 voltage for the sensor that applies to this DTC. Does the scan tool indicate that the HO2S 1 voltage is less than 20 millivolts? If yes, go to next step. If no, go to step 10.
- Turn ignition off. Remove the 3-amp fused jumper wire. Connect a test light between the ignition 1 voltage circuit and a good ground. DO NOT use the HO2S 1 heater low control. Turn ignition on, with engine off. Does the test light illuminate? If yes, go to next step. If no, go to step 11.
- Connect a test light between the ignition 1 voltage circuit and the HO2S 1 heater low control circuit. Turn ignition on, with engine off. With a scan tool, command the HO2S 1 heater ON and OFF. Does the test light turn ON and OFF with each command? If yes, go to step 14. If no, go to next step.
- Does the test light remain illuminated with each command? If yes, go to step 12. If no, go to step 13.
- Test the HO2S 1 high signal circuit for open, high resistance, short to ground or short to voltage. Did you find and correct the condition. If yes, go to step 19. If no, go to step 16.
- Test the HO2S 1 low signal circuit for an open, high resistance or short to voltage. Did you find and correct the condition? If yes, go to step 19. If no, go to step 16.
- Test the ignition 1 voltage circuit for an open, high resistance or short to ground. Replace ERLS fuse if necessary. Did you find and correct the condition? If yes, go to step 19. If no, refer to INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.
- Test the HO2S 1 low control circuit for a short to ground. Did you find and correct the condition? If yes, go to step 19. If no, go to step 16.
- Test the HO2S 1 low control circuit for an open, high resistance or short to voltage. Did you find and correct the condition? If yes, go to step 19. If no, go to step 16.
- Inspect for incorrect use of silicone RTV sealant, fuel contamination, exhaust leak, improperly installed HO2S or damaged wiring. Did you find and correct the condition? If yes, go to step 19. If no, go to next step.
- Inspect for poor connections at the harness connector of the HO2S 1. Did you find and correct the condition? If yes, go to step 19. If no, go to step 17.
- Inspect for poor connections at the harness connector of the PCM. Did you find and correct the condition? If yes, go to step 19. If no, go to step 18.
- Replace HO2S 1. When complete, go to step 19.
- Replace PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in appropriate REMOVAL, OVERHAUL & INSTALLATION article. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE REPROGRAMMING under PROGRAMMING. After replacing PCM, go to next step.
- Use the scan tool in order to clear the DTCs. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step 2.
- With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
NOTE:
If any other DTCs are set except for HO2S DTCs, refer to the other DTCs first before proceeding with this test procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
NOTE:
Before replacing the HO2S, check and remove any source of contamination.