Engine Controls - Tests W/Codes - 3.1L PFI: 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 cause of problems, 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 the basic tests in the BASIC TESTING article, proceed with DIAGNOSTIC PROCEDURE in this article. If no fault codes or only a non-running Code 12 is present and driveability problems exist, proceed to article TESTS W/O CODES 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 in this section.