Diagnostic Procedures

Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check, go to next step.

NOTE: Once engine is started, DO NOT turn engine off for the remainder of the procedure or until test is complete.

- Start and operate engine at idle.
- Ensure vehicle is within the Conditions For Running DTC.
- Set vehicle parking brake.
- Place transmission in Park (A/T) or Neutral (M/T).
- Turn off all of accessories (e.g., A/C, blower fan, etc.).
- Operate engine at idle until it reaches operating temperature of at least 158°F (70°C).
- Accelerate vehicle at part throttle to 30-50 MPH.
- Maintain speed for 2 minutes or until I/M System Status indicator updates to YES.
If status updates to YES, go to step 5 . If status does not update to YES, go to next step.
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 next step.

NOTE: Refer to INSPECTION/MAINTENANCE COMPLETE SYSTEM SET PROCEDURE to determine which DTCs are required to run in order to complete this test.

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 the Conditions For Running DTC. Monitor status of DTCs that are necessary to complete the test in the NOT RAN SINCE CODE CLEARED display of scan tool. Repeat procedure until scan tool indicates that all the necessary DTC diagnostic tests have run. Using scan tool, observe I/M System Status display. If HO2S Heater System Status updates to YES, go to next step. If status does not update to YES, go to DIAGNOSTIC AIDS .
Using scan tool, observe emission related DTC portion of I/M System Status display. If scan tool indicates any emission related DTCs are set, diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are set, system is okay.