Diagnostic Procedures
WARNING: This page is about a different car, the 2002 Pontiac Firebird and 2002 Chevrolet Camaro. However, it is still accessible from the selected car via links, so may be relevant.
- Did you perform the Diagnostic System Check-Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM.
- Install a scan tool. Idle the engine at the normal operating temperature. Operate the engine above 1200 RPM for 2 minutes. Use a scan tool in order to observe the HO2S voltage. Does the scan tool indicate the HO2S voltage varies outside 350-550 mV? If yes, go to next step. If no, go to step 4.
- Observe the Freeze Frame/Failure Records data for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC or as close to the Freeze Frame/Failure Records data that you observed. Does the DTC fail this ignition cycle? If yes, go to next step. If no, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.
- Turn ON the ignition, with the engine OFF. Disconnect the affected HO2S. Jumper the HO2S high signal circuit to a known-good ground. Jumper the HO2S low signal circuit to a known-good ground. Use a scan tool in order to observe the HO2S voltage. Is the HO2S voltage below 200 mV? If yes, go to step 8. If no, go to next step.
- Remove both jumper wires. Measure the voltage from the HO2S low signal circuit to a battery ground using the Digital Multimeter (DMM). Does the DMM indicate that the voltage is near 5 V? If yes, go to next step. If no, go to step 7.
- Turn OFF the ignition. Disconnect the PCM connector. Test the continuity of the HO2S high signal circuit. Repair the open circuit if no continuity is indicated on the DMM. Did you find and correct the condition? If yes, go to step 12. If no, go to step 10.
- Turn OFF the ignition. Disconnect the PCM connector. Test the continuity of the HO2S low signal circuit. If the DMM indicates no continuity, repair the open connection or the poor connection. Did you find and correct the condition? If yes, go to step 12. If no, go to step 10.
- Inspect the HO2S circuits for a poor connection at the HO2S harness connector. If you find a poor connection, repair the connection as necessary. Did you find and repair the condition? If yes, go to step 12. If no, go to next step.
- Replace the affected HO2S. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step 12.
- Inspect the HO2S circuits for a poor connection at the PCM. If you find a poor connection, repair the connection as necessary. Did you find and correct the condition? If yes, go to step 12. If no, go to next step.
- Replace the PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE under PROGRAMMING. After repairs, go to next step.
- Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC. Does the DTC run and pass? If yes, go to next step. If no, go to step 2.
- Observe the stored information, Capture Info with a scan tool. 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:
Important Before you proceed with this DTC, inspect the HO2S for being secure. A loose sensor can cause this DTC to set.