Engine Controls - Tests W/Codes: 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 TESTING article. Failure to do so may result in lost diagnostic time.

If no faults were found while performing BASIC TESTING article, proceed with DIAGNOSTIC PROCEDURE  under SELF-DIAGNOSTIC SYSTEM. If no Diagnostic Trouble Codes (DTCs) are present, and driveability problems exist, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.). If only intermittent DTCs are present, go to TESTS W/O CODES article.