Engine Control System Diagnosis (1 Of 2): Summary

If no Diagnostic Trouble Codes (DTCs) or pending codes, exist and driveability symptoms exist, proceed to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.). If DTC exists, but problem is not found or duplicated, problem is intermittent or problem was previously repaired and codes not cleared. See INTERMITTENT DIAGNOSTIC TROUBLE CODES .