Engine Controls - Self-Diagnostics: Introduction

Most engine control problems are the result of mechanical breakdowns, poor electrical connections or damaged vacuum hoses. Before considering the computer system as a possible cause of problems, perform checks and inspections covered in the BASIC TESTING article. Failure to do so may result in lost diagnostic time.

If no faults found performing procedures in the BASIC TESTING article, proceed with DIAGNOSTIC PROCEDURE  under SELF-DIAGNOSTIC SYSTEM. If no fault codes are present and driveability problems exist, proceed to the TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.). If only intermittent codes are present, see INTERMITTENTS in the TESTS W/O CODES article.