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Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Oldsmobile Intrigue and 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
  1. 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.
  2. If DTC P0140 is also set? If yes, go to step  4. If no, go to next step.
  3. If any other DTCs are set, repair DTCs as necessary before continuing with this test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no other DTCs are set, go to step  5.
  4. HO2S is contaminated. Check for contamination sources that may have caused HO2S to fail. HO2S contamination sources include use of an incorrect RTV silicone engine sealant, contaminated fuel and excessive engine oil or coolant consumption. Repair or remove source of contamination. Replace HO2S. After repairs, go to step  18.
  5. Turn ignition on. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC. See CONDITIONS FOR RUNNING DTC . Start engine. Ensure engine is at normal operating temperature. If DTC resets, go to step  7. If DTC does not reset, go to next step.
  6. Condition that set this DTC is not present. This DTC may have been set by one of the following conditions:
    • Exhaust leak between engine and HO2S.
    • Poor HO2S connector terminal contact.
    • Faulty HO2S heater.
    • HO2S connector water intrusion.
    • Improperly torqued HO2S. Sensor should be tightened to 30 ft. lbs. (41 Nm).
    • Poor PCM connector terminal contact.
    • An intermittent open or short in HO2S signal circuit orHO2S reference low circuit.
    • Contaminated HO2S.

    Check conditions listed for faults. If any problems are found, repair as necessary. After repairs, go to step  18. If no problems were found, see DIAGNOSTIC AIDS .

  7. Check exhaust system for leaks between HO2S and engine. Repair exhaust as necessary. Check HO2S and PCM connectors for correct terminal contact. Repair terminal contact as necessary. Did you complete the repair? If yes, go to step  18. If no, go to next step.
  8. Turn ignition off. Disconnect HO2S connector. Jumper engine harness side of HO2S low reference circuit terminal to a known-good ground. Turn ignition on, with engine off. Use scan tool in order to monitor the HO2S voltage for the sensor that applies to this DTC. Is HO2S voltage within 351-551 millivolts? If yes, go to next step. If no, go to step  13.
  9. Jumper HO2S high signal circuit to ground. Use scan tool in order to monitor the HO2S voltage for the sensor that applies to this DTC. Is HO2S voltage less than 20 millivolts? If yes, go to next step. If no, go to step  14.
  10. Remove HO2S low reference circuit jumper. Connect a test light between the engine harness side of the HO2S ignition 1 voltage circuit terminal and a known-good ground. DO NOT use HO2S heater low control circuit terminal. Does the test light illuminate? If yes, go to next step. If no, go to step  15.
  11. Connect test light between the engine harness side of HO2S ignition 1 voltage circuit terminal and engine harness side of HO2S heater low control circuit terminal. Start engine. Does test light illuminate? If yes, go to next step. If no, go to step  16.
  12. Check for contamination sources that may have caused HO2S to fail. HO2S contamination sources include use of an incorrect RTV silicone engine sealant, contaminated fuel and excessive engine oil or coolant consumption. Repair or remove source of contamination. After repairs, go to step  17.
  13. Turn ignition off. Check HO2S high signal circuit as follows:
    • A short between HO2S high and low circuits or between HO2S high signal circuit and ground.
    • A short between HO2S high signal circuit and an ignition voltage source.

    Repair HO2S high signal circuit as necessary. After repairs, go to step  18.

  14. Check the HO2S high signal circuit or HO2S low reference circuit for an open or high circuit resistance. Repair HO2S circuits as necessary. After repairs, go to step  18.
  15. Repair HO2S ignition 1 voltage circuit. After repairs, go to step  18.
  16. Repair HO2S heater low control circuit. After repairs, go to step  18.
  17. Replace HO2S. After repairs, go to next step.
  18. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC. See CONDITIONS FOR RUNNING DTC . If DTC runs and passes, go to next step. If DTC resets, go to step  2.
  19. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, system is okay. If any other DTCs are set, repair DTCs as necessary. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
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