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Home >> Oldsmobile >> 1998 >> Regency >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control Systems Tests W/Codes >> Diagnostic Trouble Codes >> DTC P0135 - Ho2S 1 Heater Circuit >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . Read and record FREEZE FRAME and/or FAIL RECORDS data for each DTC set. After performing OBD system check, go to next step.
    NOTE: If engine has been operating, allow engine to cool down for about 30 minutes before proceeding with tests.
  2. Turn ignition on, with engine off. Using scan tool, read HO2S 1 voltage. If voltage is greater than 0.6 volt or less than 0.3 volt, see DIAGNOSTIC AIDS. If voltage is not greater than 0.6 volt or not less than 0.3 volt, go to next step.
  3. Inspect HO2S 1 ignition feed fuse. If fuse is open, go to step 15). If fuse is okay, go to next step.
  4. Turn ignition off. Raise and support vehicle. Disconnect HO2S 1 harness connector. Connect a test light between ground and HO2S 1 ignition feed circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 7).
  5. Connect test light between HO2S 1 harness connector ignition feed and heater ground circuits. If test light illuminates, go to next step. If test light does not illuminate, go to step 8).
  6. Allow HO2S 1 to cool down for at least 10 minutes. Using DVOM, check resistance between ignition feed and heater ground circuits at HO2S 1. If resistance is 3-10 ohms, go to step 9). If resistance is not 3-10 ohms, go to step 14).
  7. Repair open in HO2S 1 ignition feed circuit. After repairs, go to step 16).
  8. Repair open in HO2S 1 heater ground circuit. After repairs, go to step 16).
  9. Check for faulty connection at HO2S 1. Repair as necessary. After repairs, go to step 16). If connection is okay, go to next step.
  10. Turn ignition off. Disconnect PCM connectors. Check resistance of HO2S 1 signal and ground circuits. If resistance on either circuit is greater than 5 ohms, repair open or faulty connection as necessary. After repairs, go to step 16). If resistance is 5 ohms or less, go to next step.
  11. Check for faulty connection at HO2S 1 harness connector. Repair as necessary. After repairs, go to step 16). If connection is okay, go to next step.
  12. Check for faulty ground circuit connection at PCM. Repair as necessary. After repairs, go to step 16). If connection is okay, go to next step.
  13. Check for faulty HO2S 1 signal circuit connection at PCM. Repair as necessary. After repairs, go to step 16). If connection is okay, go to next step.
  14. Replace HO2S 1. After replacing sensor, go to step 16).
  15. Locate and repair short to ground in HO2S 1 ignition feed circuit, replace fuse. After repairs, go to next step.
  16. Allow engine to cool completely. Using scan tool, clear DTCs. Turn ignition on, engine off. Read HO2S 1 voltage. If voltage is greater than 0.6 volt or less than 0.3 volt, repair is complete. If voltage is not greater than 0.6 volt or less than 0.3 volt, return to step 2).
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