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Home >> Buick >> 1996 >> Century Custom >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes - 2.2L >> Diagnostic Trouble Codes >> DTC P1133 - O2S Insufficient Switching Sensor 1 >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. If other DTCs are present, diagnose affected DTCs. If no other DTCs are present, go to next step.
  3. Start engine. Ensure engine is at normal operating temperature. Operate vehicle within the conditions required for setting this DTC. Using scan tool, monitor LEAN/RICH transition and note number of switches. Also, note number of RICH/LEAN transitions. If LEAN/RICH transitions are less than 15 and RICH/LEAN transitions are less than 10, go to next step. If LEAN/RICH transitions are 15 or greater and RICH/LEAN transitions are 10 or greater, go to step 18). If LEAN/RICH transitions are 40 or greater and RICH/LEAN transitions are 30 or greater, go to step 18).
  4. Inspect the following:
    • Check for proper O2S 1 installation.
    • Check O2S 1 connector and wiring for corrosion or damage.
    • Check O2S 1 ground circuit.

    Repair as necessary. After repair is completed, go to step 9). If no problems were found, go to next step.

  5. Check exhaust manifold for leaks. Repair as necessary. After repair is completed, repeat step 3). If exhaust is okay, go to next step.
  6. Disconnect O2S 1 connector. Turn ignition on. Using scan tool, monitor O2S 1 voltage. If voltage is 407-509 mV, go to next step. If voltage is not 407-509 mV, go to step 10).
  7. Connect a jumper wire between ground and signal circuit terminal at O2S 1 harness connector. If voltage is less than 200 mV, go to next step. If voltage is 200 mV or greater, go to step 11).
  8. Replace oxygen sensor. Determine cause of sensor contamination, otherwise new sensor will be damaged. After repair is completed, go to step 17).
  9. Repair wiring or terminal as necessary. DO NOT attempt to repair damaged oxygen sensor connector or wiring. If damage is detected, replace oxygen sensor. After repair is completed, go to step 17).
  10. Repair short to ground in O2S 1 signal circuit. After repair is completed, go to step 17).
  11. Remove jumper wire. Measure voltage between ground and signal circuit at O2S 1 harness connector. If voltage is greater than 407 mV, go to next step. If voltage is 407 mV or less, go to step 13).
  12. Turn ignition off. Disconnect PCM connectors. Measure resistance between ground and O2S 1 ground circuit at PCM connector. If resistance is less than 5 ohms, go to step 14). If resistance is 5 ohms or greater, repair open in ground circuit. After repair is completed, go to step 17).
  13. Turn ignition off. Disconnect PCM connectors. Measure resistance of signal circuit between O2S 1 harness connector and PCM connector. If resistance is less than 5 ohms, go to step 15). If resistance is 5 ohms or greater, repair open in sensor signal circuit. After repair is completed, go to step 17).
  14. Check O2S 1 ground circuit terminal connection at PCM connector. Repair or replace terminal as necessary. After repair is completed, go to step 17). If ground circuit terminal is okay, go to step 16).
  15. Check O2S 1 signal circuit terminal connection at PCM connector. Repair or replace terminal as necessary. After repair is completed, go to step 17). If ground circuit terminal is okay, go to next step.
  16. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
  17. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P1133. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2).
  18. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, go to DIAGNOSTIC AIDS.
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