Engine Controls - Self Diagnostics - Introduction: 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 PROCEDURES article. Failure to do so may result in lost diagnostic time.

If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed with PRELIMINARY DIAGNOSTIC PROCEDURE  under SELF-DIAGNOSTIC SYSTEM. If no Diagnostic Trouble Codes (DTCs) are present, and driveability problems exist, proceed to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., rough idle, no start, etc.). If only intermittent DTCs are present, go to TROUBLE SHOOTING - NO CODES article.