Engine Controls - Self-Diagnostics: Introduction

Most engine control problems result from mechanical failures, poor electrical connections or damaged vacuum hoses. Before condemning the computer system, perform checks and inspections covered in BASIC DIAGNOSTIC PROCEDURE article. Failure to do so may result in lost diagnostic time.

If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES , proceed with self-diagnostics. If no fault codes are present after entering self-diagnostics, proceed to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.). If DTC exists, but problem cannot be found or duplicated, problem is intermittent or problem was previously repaired and codes not cleared.