Engine Controls - Basic Diagnostic Procedures: Summary

If no faults were found while performing basic diagnostic procedures, or no trouble codes (or only intermittent ones) were found while performing On-Board Diagnostic (OBD) system check, and driveability problems still exist, proceed to appropriate TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO-START, etc.) or intermittent diagnostic procedures.