On-Board Diagnostic (OBD) System Check: Notes

NOTE: Tech 1 or Tech 2 scan tool is required to perform OBD system check.

The OBD system check determines:

If Service Engine Soon (SES), also called Malfunction Indicator Light (MIL) operates.
If PCM is operating and can recognize a fault.
If any DTCs are stored.

After performing procedures in PRELIMINARY INSPECTION & ADJUSTMENTS, BASIC FUEL SYSTEM CHECKS and BASIC IGNITION SYSTEM CHECKS in appropriate BASIC DIAGNOSTIC PROCEDURES article, this is the starting point for utilizing the self-diagnostic system for determining computer-related problems. After performing necessary tests as described in the OBD system check, if no codes are indicated and driveability problems still exist, see appropriate TROUBLE SHOOTING - NO CODES article and SCAN TOOL USAGE .