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Home >> Pontiac >> 2002 >> Aztek AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics >> Diagnostic Tests >> DTC P0141: Ho2S Heater Circuit - Sensor 2 >> Diagnostic Procedures
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Diagnostic Procedures

  1. 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.
    2. NOTE: If the engine has just been operating, allow engine to cool until near bias voltage is observed on the scan tool before proceeding.
  2. Turn ON the ignition, with the engine OFF. Monitor HO2S 2 voltage on the scan tool. Does the HO2S 2 voltage go to above or below the previously stabilized voltage, by at least 100 mV within 2 minutes? If yes, go to next step. If no, go to step  4.
  3. 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.
    4. NOTE: The test lamp must be connected to a good ground.
  4. Disconnect the HO2S 2 electrical connector. Turn ON the ignition, with the engine OFF. Connect a test lamp between the HO2S 2 heater ignition voltage circuit, in the harness side of the HO2S connector, and ground. Does the test lamp illuminate? If yes, go to next step. If no, go to step  7.
  5. Turn OFF the ignition. Connect a test lamp between the HO2S 2 heater ignition voltage circuit, in the harness side of the HO2S connector, and the HO2S 2 heater ground circuit. Turn ON the ignition, with the engine OFF. Does the test lamp illuminate? If yes, go to next step. If no, go to step  10.
    6. NOTE: The heater element resistance will vary according to HO2S temperature. A hot HO2S heater element will have a higher resistance than at room temperature.
  6. Turn OFF the ignition. Leave the HO2S connector disconnected. Allow the engine to cool for at least 15 minutes. Measure the HO2S 2 heater resistance at the HO2S 2 pigtail connector using a Digital Multimeter (DMM). Resistance should be 2-20 ohms. When complete, go to step  11.
  7. Test the HO2S 2 heater ignition voltage circuit for an open fuse. Did you find an open fuse? If yes, go to next step. If no, go to step  9.
  8. Locate and repair the short to ground in the HO2S 2 heater ignition voltage circuit and replace the fuse. After repairs, go to step  13.
  9. Repair the open or high resistance condition in the HO2S 2 heater ignition voltage circuit. After repairs, go to step  13.
  10. Repair the open or high resistance condition in the HO2S 2 heater ground circuit. After repairs, go to step  13.
  11. Before continuing, inspect for poor connections at the HO2S 2 connector. Did you find and correct the condition? If yes, go to step  13. If no, go to next step.
  12. Replace the HO2S 2. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to next step.
  13. 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.
  14. 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.
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