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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 375 (Engine Controls Self-Diagnostics) >> Diagnostic Tests >> DTC P0135, P0141, P0155 & P0161: Ho2S Heater Circuit - Bank 1 & 2, Sensors 1 & 2 >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Chevrolet Corvette. 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, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
    2. NOTE: Allow the engine to cool for one-half hour before proceeding with this diagnosis. If DTC P0300 is set, diagnose that DTC first. See DTC P0300: ENGINE MISFIRE DETECTED .
  2. Turn ignition OFF. Install a scan tool. Turn ignition ON, with engine OFF. Immediately observe affected HO2S voltage for 2 minutes. Does HO2S voltage go from bias voltage to greater than or less than 300-600 mV? If yes, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM. If no, go to next step.
  3. Inspect HO2S fuse for an open. Is HO2S fuse open? If yes, go to step  11. If no, go to next step.
  4. Raise and support vehicle. Disconnect HO2S electrical connector. Probe ignition 3 voltage circuit at the PCM side of the HO2S electrical connector using a test light connected to a good ground. Do not use the HO2S heater ground or the HO2S low signal circuits. Does the test light illuminate? If yes, go to next step. If no, go to step  7.
  5. Connect test light between the HO2S ignition 3 voltage and HO2S heater ground. Does the test light illuminate? If yes, go to next step. If no, go to step  8.
  6. Measure the resistance between HO2S ignition 3 voltage and HO2S heater ground at the HO2S pigtail. Is the HO2S resistance 2-50 ohms? If yes, go to step  9. If no, go to step  10.
  7. Repair open in HO2S ignition 3 voltage circuit to the HO2S. Did you complete the repair? If yes, go to step  12.
  8. Repair open in HO2S heater ground circuit. Did you complete the repair? If yes, go to step  12.
  9. Test for an intermittent and/or poor connections at the HO2S harness terminals. If you find a poor connection, repair the terminal as necessary. Did you find and repair the condition? If yes, go to step  12. If no, go to next step.
  10. Replace affected HO2S. See HEATED OXYGEN SENSOR under SENSORS in REMOVAL & INSTALLATION - CORVETTE article. Did you complete the replacement? If yes, go to step  12.
  11. Locate and repair short to ground in HO2S ignition 3 voltage circuit. Replace the open fuse. Did you complete the repair? If yes, go to next step.
  12. 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 the 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 cycle? If yes, go to step  2. If no, go to next step.
  13. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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