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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 335 (Engine Controls - Self-Diagnostics - 3.0L) >> Diagnostic Tests >> DTC P0135, P0141, P0155 0R P0161: Ho2S Heater Circuit >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Saturn Vue. 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 .
  2. Operate the engine at normal operating temperature. Operate the engine at greater than 1200 RPM for 2 minutes. Quickly cycle the throttle from closed throttle to wide open throttle 3 times while observing the affected HO2S voltage parameter with a scan tool. Does the affected HO2S voltage react immediately? If yes, go to next step. If no, go to step  4.
  3. Observe the Freeze Frame/Failure Records for this DTC. Turn ignition off for 60 seconds. Start engine. Operate vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . 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, problem is intermittent. Refer to INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 2.2L & 3.0L VUE article.
  4. Turn ignition off. Disconnect the affected HO2S sensor. Turn ignition on, with engine off. Observe the voltage parameter with a scan tool. Is the HO2S voltage parameter within 425-475 mV? If yes, go to next step. If no, go to step  9.
  5. Connect a 3-amp fused jumper wire between the HO2S high signal circuit on the engine harness side and a good ground. Observe the HO2S voltage parameter with a scan tool. Is the voltage less than 35 mV? If yes, go to next step. If no, go to step  12.
  6. Remove the jumper wire from the previous step. Connect a 3-amp fused jumper wire between the HO2S high signal circuit and the HO2S low signal circuit on the engine harness side. Observe the HO2S voltage parameter with a scan tool. Is the voltage less than 35 mV? If yes, go to next step. If no, go to step  13.
  7. Remove the jumper wire from the previous step. Turn ignition off. Measure the resistance of the affected HO2S heater ignition 1 voltage supply circuit between the HO2S harness connector and the appropriate ignition voltage fuse. Is the resistance less than 5 ohms? If yes, go to next step. If no, go to step  14.
  8. Measure the resistance of the affected HO2S heater low control circuit between the HO2S harness connector and the ECM. Is the resistance less than 5 ohms? If yes, go to step  16. If no, go to step  15.
  9. Measure the voltage from the HO2S high signal circuit on the engine harness side to a good ground with a DVOM. Is the voltage more than 475 mV? If yes, go to next step. If no, go to step  11.
  10. Test the HO2S high signal circuit for a short to voltage or for a short to the heater low control circuit. Did you find and correct the condition? If yes, go to step  21. If no, go to step  17.
  11. Test the HO2S high signal circuit for a short to ground. Did you find and correct the condition? If yes, go to step  21. If no, go to step  17.
  12. Test the HO2S high signal circuit for an open or for high resistance. Did you find and correct the condition? If yes, go to step  21. If no, go to step  17.
  13. Test the HO2S low signal circuit for an open or for high resistance. Did you find and correct the condition? If yes, go to step  21. If no, go to step  17.
  14. Repair HO2S heater voltage supply circuit open or the high resistance. After repairs, go to step  21.
  15. Repair HO2S heater low control circuit open or the high resistance. After repairs, go to step  21.
  16. The HO2S is detecting a rich or lean exhaust condition or may be contaminated. Inspect HO2S connector for water intrusion or HO2S for silicone or engine oil contamination. Inspect for incorrect fuel pressure or leaking fuel pressure regulator. Repair any of the conditions as necessary. Did you find and correct the condition? If yes, go to step  21. If no, go to step  18.
  17. Test for shorted terminals and poor connections at the ECM. Did you find and correct the condition? If yes, go to step  21. If no, go to step  20.
  18. Test for shorted terminals and poor connections at the HO2S harness connector. Did you find and correct the condition? If yes, go to step  21. If no, go to next step.
  19. Replace affected HO2S. After replacing sensor, go to step  21.
  20. Replace ECM. Perform ECM relearn procedures. See ENGINE CONTROL MODULE  under PROGRAMMING. After replacing ECM, go to next step.
  21. Clear the DTCs with a scan tool. Turn ignition off for 60 seconds. Start engine. Operate vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . 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.
  22. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? If yes, diagnose affected DTC(s). See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are displayed, system is okay.
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