LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Cadillac >> 2002 >> Eldorado ECS >> Repair and Diagnosis >> External Pages >> Different car >> Section 249 (Engine Controls Self-Diagnostics - 2.2L) >> Drive Cycles >> Inspection/Maintenance Heated Oxygen Sensor/Oxygen Sensor System Set Procedure >> Diagnostic Procedures
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 GMC Sonoma and 2003 Chevrolet S10 Pickup. However, it is still accessible from the selected car via links, so may be relevant.
  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 vehicle is within the Conditions For Running DTC. See CONDITIONS FOR RUNNING DTC  . Turn off all accessories (e.g., A/C, blower fan, etc.). Start engine and allow to idle.
    • Accelerate vehicle at part throttle to 45-55 MPH and maintain speed for 6 minutes or until I/M System Status updates to YES.
    • Vehicles equipped with 5 or 6-speed manual transmission, may require operation in 4th or 5th gear respectively, in order for this test to run.

    Using scan tool, review I/M System Status display. Did HO2S/O2S system status updates to YES? If yes, go to step  5 . If no, go to next step.

  3. Using a scan tool, observe the DTC Information. Does scan tool indicate any failed DTCs? If yes, diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no, 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. Enter DTC number in the Specific DTC menu of scan tool. Operate vehicle within the Conditions For Running the DTC. See CONDITIONS FOR RUNNING DTC  . Repeat the 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 the I/M System Status display. Did the HO2S/O2S system status updates 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 scan tool indicates any emission related DTCs set? If yes, diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no, system is okay.
scientia non olet · About LEMON Manuals