Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. 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, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM.

NOTE: If any other DTCs are set except the HO2S DTCs, diagnose the other DTCs first before proceeding with this procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .

Ensure that the engine is at the operating temperature. Operate the engine above 1200 RPM for 2 minutes. With a scan tool, observe the HO2S voltage parameter. Does the voltage vary outside 325-625 mV? If yes, go to next step. If no, go to step 4.
Review and record the scan tool Failure Records. Operate the vehicle within the Conditions for Running DTC. Using the scan tool, observe the Specific DTC Information for DTC P0153 until the test runs. Does the scan tool indicate that DTC P0153 is current? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
Inspect for the following items:
- Exhaust leak.
- The HO2S is installed correctly.
- Damaged wiring.
Did you find and correct the condition? If yes, go to step 13. If no, go to next step.
Turn OFF the ignition. Disconnect the HO2S. Turn ON the ignition. Using the DMM, measure the voltage between the HO2S signal circuit on the PCM side and a good ground. Does the voltage measure near 450 mV? If yes, go to next step. If no, go to step 8.
Jumper the high signal circuit to the low signal circuit on the PCM side. With a scan tool, observe the HO2S voltage parameter. Does the voltage measure near 0 mV? If yes, go to step 9. If no, go to next step.
Test the low signal circuit for an open or high resistance. If the condition is found, repair as necessary. Did you find and correct the condition? If yes, go to step 13. If no, go to step 11.
Test the high signal circuit for an open or for high resistance. If an open/high resistance condition is found, repair as necessary. Did you find and correct the condition? If yes, go to step 13. If no, go to step 11.
Test for poor connections at the HO2S. If a poor connection condition is found, repair as necessary. Did you find and correct the condition? If yes, go to step 13. If no, go to next step.

NOTE: Contamination of the oxygen sensor can result from the use of an inappropriate RTV sealant (not oxygen sensor safe) or excessive engine coolant or oil consumption. Remove the HO2S and visually inspect the portion of the sensor exposed to the exhaust stream in order to check for contamination. If contaminated, the portion of the sensor exposed to the exhaust stream will have a White powdery coating. Silicone contamination causes a high but false HO2S signal voltage (rich exhaust indication). The control module will then reduce the amount of fuel delivered to the engine, causing a severe driveability problem. Eliminate the source of contamination before replacing the oxygen sensor. Determine the cause of contamination before replacing the sensor.

Inspect and test for the following conditions:
- Fuel contamination.
- Engine oil or coolant consumption.
- Use of improper RTV sealant.
Replace the HO2S. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step 13.
Test for poor connections at the PCM. Did you find and correct the condition? If yes, go to step 13. 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.
Use the scan tool in order to clear the DTCs. 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.
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.