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HOMESERVICE MANUALSBUICK1999REGAL LSREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROL SYSTEM - TESTS W/CODES - DTC P0704-P1272DTC P1133DTC P1133: HO2S INSUFFICIENT SWITCHING BANK 1, SENSOR 1 (5.7L "F" & "Y" BODIES)DIAGNOSTIC PROCEDURES
1999 Buick Regal LS

Diagnostic Procedures

1999 Buick Regal LSSECTION Diagnostic Procedures
  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
    2. NOTE: If other DTCs are present (except DTC P1153), diagnose affected DTC(s) first.
  2. Start and warm engine to normal operating temperature. Using scan tool, monitor FAIL THIS IGN under DTC info. If scan tool indicates that DTC P1133 test failed this ignition cycle, go to next step. If scan tool does not indicate that this test failed this ignition cycle, see DIAGNOSTIC AIDS .
  3. If scan tool indicates that DTC P1153 test failed, go to step  8. If scan tool does not indicate that DTC P1153 test failed, go to next step.
  4. Check exhaust system for leaks. Repair as necessary. After repairs, go to step 14. If exhaust leak is not present, go to next step.
  5. Ensure that HO2S is securely installed. Check for corrosion on terminals and terminal tension at sensor and PCM. Check for damaged wiring. Repair as necessary. After repairs, go to step 14. If no problems were found, go to next step.
  6. Disconnect HO2S. Connect a fused jumper wire between ground and PCM connector (PCM side), HO2S low signal circuit. Using scan tool, select ENGINE 1 DATA LIST and monitor HO2S voltage. If HO2S voltage is within a range of 350-550 mV, go to next step. If HO2S voltage is not as specified, go to step  10.
  7. Connect a fused jumper wire between ground and HO2S high and low signal circuits. Using scan tool, monitor voltage. If voltage reading is less than 200 mV, go to step  13. If voltage reading is greater than 200 mV, go to step  9.
  8. Replace affected oxygen sensor. Determine cause of sensor contamination, otherwise new sensor will be damaged. After replacing oxygen sensor, go to step  14.
  9. Remove jumper wire from HO2S low circuit. Check voltage between battery ground and HO2S low signal circuit. If voltage reading is volts, go to step  12. If voltage reading is not 5 volts, go to step  11.
  10. Repair short to ground or voltage in high signal circuit. After repairs, go to step  14.
  11. Repair open in sensor low signal circuit or faulty PCM connectors. After repairs, go to step  14.
  12. Repair open in sensor high signal circuit or faulty PCM connectors. After repairs, go to step  14.
  13. Replace HO2S. After replacing oxygen sensor, go to next step.
  14. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step  2.
  15. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.