Section 80 (Engine Controls - Basic Diagnostic Procedures): Introduction

WARNING: This page does not describe the selected car, but rather 35 other vehicles, including the 2003 BMW Z8, 2003 BMW Z4, 2003 BMW X5, 2003 BMW M5, and 2003 BMW M3. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Vehicles are equipped with an OBD-II diagnostic system. For thorough and complete diagnosis, manufacturer strongly recommends the purchase of BMW-specific diagnostic equipment. For diagnosis, see 2002 SELF-DIAGNOSTICS , 2003 SELF-DIAGNOSTICS - Except 7-Series or 2003 SELF DIAGNOSTICS - 7-Series article.

The following diagnostic steps will help prevent overlooking a simple problem. This is also where to begin diagnosis for a no-start condition. The first step in diagnosing any driveability problem is verifying the problem with a test drive under the conditions the problem reportedly occurred.

Before entering self-diagnostics, perform a careful and complete visual inspection. Most engine control problems result from mechanical breakdowns, poor electrical connections or damaged/misrouted vacuum hoses. Before condemning the computerized system, perform each test listed in this article.

NOTE: Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure.