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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 379 (Engine Controls Self-Diagnostics - 3.4L) >> Diagnostic Tests >> DTC P0141: Ho2S 2 Heater Performance >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Pontiac Grand Am, 2003 Oldsmobile Alero, 2003 Chevrolet Monte Carlo, and 2003 Chevrolet Impala. 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. Using the scan tool, Monitor the HO2S 2 voltage parameter 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. See CONDITIONS FOR RUNNING . 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 - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
    4. NOTE: Use a known good ground. DO NOT use the HO2S 2 low signal circuit.
  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, on 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  6.
  5. Turn ignition switch to OFF position. Connect a test light between the HO2S 2 heater ignition voltage circuit and the HO2S 2 heater ground circuit on the engine harness side. Turn ignition switch to RUN position, engine off. Does the test light illuminate? If yes, go to step  7. If no, go to step  10.
  6. Check 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.
  7. Check for an intermittent and for a poor connection at the harness connector of the HO2S 2. Did you find and correct the condition? If yes, go to step  12. If no, go to step  11.
  8. Repair the short to ground in the HO2S 2 heater ignition voltage circuit and replace the fuse. After repair, go to step  12.
  9. Repair the open or high resistance in the HO2S 2 heater ignition voltage circuit. After repair, go to step  12.
  10. Repair the open or high resistance in the HO2S 2 heater ground circuit? After repair, go to step  12.
  11. Replace the HO2S 2. After repair, go to step  12.
  12. 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. See CONDITIONS FOR RUNNING . 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.
  13. 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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