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Home >> Buick >> 2001 >> Regal LS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 3.8L >> Diagnostic Tests >> DTC P0134: Ho2S Circuit Insufficient Activity - Bank 1, Sensor 1 >> Diagnostic Procedures
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Diagnostic Procedures

NOTE: If any other DTCs are set, except HO2S DTCs, diagnose other DTCs first before proceeding with this procedure.
  1. Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing powertrain diagnostic system check, go to next step.
  2. Ensure engine is at operating temperature. Operate engine at more than 1200 RPM for 2 minutes. Using scan tool, observe HO2S voltage parameter. If scan tool indicates HO2S voltage varies outside 400-500 millivolts, go to next step. If scan tool does not indicate HO2S voltage varies outside 400-500 millivolts, go to step  4.
  3. Using scan tool, observe FREEZE FRAME/FAILURE RECORDS data. Operate vehicle within FREEZE FRAME/FAILURE RECORDS data conditions. If scan tool indicates DTC failed this ignition cycle, go to next step. If scan tool indicates DTC did not fail this ignition cycle, see INTERMITTENT TROUBLE CODE DETERMINATION  under ON-BOARD DIAGNOSTICS under SELF-DIAGNOSTIC SYSTEM.
  4. Check for an exhaust leak, correct HO2S installation, and damaged wiring. If problem was found, repair as necessary. After repairs, go to step  15. If problem was not found, go to next step.
  5. Turn ignition on. Disconnect HO2S. See Figure or Figure . Connect jumper wire between HO2S connector terminal "B" (Purple wire) and ground. See Figure. Using scan tool, observe HO2S voltage parameter. If scan tool indicates HO2S voltage is more than 400 millivolts, go to next step. If scan tool does not indicate HO2S voltage is more than 400 millivolts, go to step  10.
  6. Remove jumper wire. Using a DVOM connected to ground, measure voltage on HO2S connector terminal "B" (Purple wire). If voltage is about 4.5 volts, go to next step. If voltage is not about 4.5 volts, go to step  9.
  7. Using a DVOM connected to ground, measure voltage on HO2S connector terminal "A" (Tan wire). If voltage is about 5 volts, go to step  11. If voltage is not about 5 volts, go to next step.
  8. Check Tan wire between HO2S and PCM for open or high resistance. If problem was found, repair as necessary. After repairs, go to step  15. If problem was not found, go to step  13.
  9. Check Purple wire between HO2S and PCM for open or high resistance. If problem was found, repair as necessary. After repairs, go to step  15. If problem was not found, go to step  13.
  10. Check Tan wire between HO2S and PCM for short to ground. If problem was found, repair as necessary. After repairs, go to step  15. If problem was not found, go to step  14.
  11. Check HO2S connector for poor connections. If problem was found, repair as necessary. After repairs, go to step  15. If problem was not found, go to next step.
    12. NOTE: Determine cause of contamination before replacing sensor.
  12. Inspect for fuel contamination, engine oil or coolant consumption, use of an improper RTV sealant. Remove HO2S and visually inspect portion of sensor exposed to exhaust stream in order to check for contamination. If contaminated, portion of sensor exposed to exhaust stream will have a White powdery coating. Silicone contamination causes a high but false HO2S signal voltage (rich exhaust indication). Control module will then reduce amount of fuel delivered to engine, causing a severe driveability problem. Eliminate source of contamination before replacing oxygen sensor. Replace HO2S sensor. After repairs, go to step  15.
  13. Check PCM connectors for poor connections. If problem was found, repair as necessary. After repairs, go to step  15. If problem was not found, go to next step.
  14. Replace PCM. Program replacement PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  15. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria. If DTC runs and passes, go to next step. If DTC does not run and pass, go to step  2.
  16. Using scan tool, observe stored information. If scan tool displays any DTCs that have not been diagnosed, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If scan tool does not display any DTCs, system is okay.
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