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Home >> Buick >> 2002 >> Century Custom >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 3.1L Engine >> Inspection/Maintenance Procedures >> Inspection/Maintenance Heated Oxygen Sensor/Oxygen Sensor (Ho2S/O2S) System Set Procedure >> Diagnostic Procedures
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Diagnostic Procedures

  1. Did you perform the Inspection/Maintenance (I/M) System Check? If yes, go to next step. If no, go to INSPECTION/MAINTENANCE SYSTEM CHECK .
    WARNING: Road test vehicle under safe conditions and while obeying all traffic laws. Do not attempt any maneuvers that could jeopardize vehicle control. Failure to adhere to these precautions could lead to serious personal injury and vehicle damage.
  2. Ensure the vehicle is within the Conditions for Running test. See CONDITIONS FOR RUNNING TEST . Turn off all of the accessories, e.g., A/C, blower fan, etc. Start and idle engine. Important: In order for this test to run, the vehicle must operate in the following conditions: Accelerate vehicle to 45-55 MPH and operate vehicle within the specified speed for 6 minutes or until the I/M system Status updates to YES. On M/T, either 5 or 6-speed, may require operation in 4th or 5th gear respectively, in order for this test to run. With a scan tool, review the I/M system Status display. Did the HO2S/O2S system Status update to YES? If yes, go to step  5. If no, go to next step.
  3. Using scan tool, observe DTC Information. If scan tool indicates any failed DTCs, diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If scan tool does not indicate any failed DTCs, go to next step.
    NOTE: Refer to INSPECTION/MAINTENANCE SYSTEM DTCS  to determine which DTCs are required to run in order to complete this test.
  4. Using scan tool, observe the NOT RAN SINCE CODE CLEARED display. Determine which of the DTCs required for a YES status has not run. Operate vehicle within Conditions For Running Test. See CONDITIONS FOR RUNNING TEST . Monitor status of DTCs that are necessary to complete the test in the NOT RAN SINCE CODE CLEARED display of scan tool. Repeat this procedure until scan tool indicates the diagnostic test has run. Repeat this step for any additional required DTCs that have not run. Using scan tool, observe I/M system Status display. Did the HO2S/O2S system Status update to YES? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
  5. Using scan tool, observe the emission related DTC portion of the I/M system Status display. Does the scan tool indicate any Emission Related DTCs set? If yes, diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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