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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 378 (Engine Controls Self-Diagnostics - 3.1L Engine) >> Diagnostic Tests >> DTC P0141: Ho2S 2 Heater Performance >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2003 Pontiac Grand Prix, 2003 Chevrolet Malibu, and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
  1. 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.
    2. NOTE: If the engine has just been operating, allow engine to cool until the Heated Oxygen Sensor (HO2S) 2 voltage is stable, or near the bias voltage before proceeding.
  2. Turn ignition switch to RUN position, engine OFF. Monitor the HO2S 2 voltage using a scan tool. Does the HO2S 2 voltage go above or below the previously stabilized voltage by at least as much as 100 mV within 2 minutes? If yes, go to next step. If no, go to step  4.
  3. Observe the Freeze Frame/Failure Records for this DTC. Turn ignition switch to OFF position for 30 seconds. Start the engine. Operate the vehicle within the Conditions For Running Test. See CONDITIONS FOR RUNNING TEST . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to next step. If no, go to INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 3.1L CENTURY, GRAND PRIX & MALIBU article.
    4. NOTE: The test light must be connected to a good ground.
  4. Turn ignition switch to OFF position. Disconnect the HO2S 2 harness connector. Turn ignition switch to RUN position, engine OFF. Connect a test light between the HO2S 2 heater ignition voltage circuit at the engine harness side of the HO2S connector and a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step  7.
  5. Turn ignition switch to OFF position. Connect a test light between the HO2S 2 heater ignition voltage circuit, of the engine harness, and the HO2S 2 heater ground circuit of the engine harness. Turn ignition switch to RUN position, engine OFF. Does the test light 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 ignition switch to OFF position. Leave the HO2S connector disconnected. Allow the engine to cool for at least 15 minutes. Measure the resistance from the HO2S heater ignition circuit to the heater ground circuit of the HO2S. Is the resistance 2-20 ohms? If yes, go to next step. If no, go to step  11.
  7. Test the HO2S 2 heater ignition voltage circuit fuse for an open. Did you find an open fuse? If yes, go to next step. If no, go to step  9.
  8. Repair the short to ground in the HO2S 2 heater ignition voltage circuit and replace the fuse. After repair, go to step  13.
  9. Repair the open or high resistance in the HO2S 2 heater ignition voltage circuit. After repair, go to step  13.
  10. Repair the open or high resistance in the HO2S 2 heater ground circuit. After repair, go to step  13.
  11. Test for an intermittent and for a poor connection at the HO2S 2 harness 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. After repair, go to next step.
  13. Clear the DTCs using a scan tool. Turn ignition switch to OFF position for 30 seconds. Start the engine. Operate the vehicle within the Conditions For Running Test. See CONDITIONS FOR RUNNING TEST . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to step  2. If no, go to next step.
  14. Using the scan tool, observe the stored information in 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 at this time.
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