October 30: LEMON manuals on a temporary server, it is slow and having issues, download the manuals you need! Later in November we will switch back to the fast server.

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 OBD system check, and driveability problems still exist, proceed to TROUBLE SHOOTING - NO CODES - TRUCKS article for diagnosis by symptom (i.e., ROUGH IDLE, NO-START, etc.) or intermittent diagnostic procedures.