Diagnostic Guidelines (Start Here)

SYSTEM INFORMATION
In the event of a Digital Motor Electronic (DME) system malfunction, circuit information will be stored in the internal memory of the DME control unit. The DME control unit is able to store up to fifteen malfunctions and will give priority to those items which can cause the vehicle to exceed exhaust emission standards. Intermittent failures are stored with a record of the failure frequency. In addition to being stored in memory, an emissions-related failure will cause the "Check Engine" light to illuminate on the instrument cluster.

The "Check Engine" light is also used to display faults which are stored in the control unit's memory. When the self-diagnostic procedure is initiated, the DME control module pulses the number of the trouble code via the "Check Engine" light.

NOTE: Only malfunctions which would cause the vehicle to fail to comply with emission certification standards will be displayed via the "Check Engine" light. This flash-code system is not a substitute for the BMW Service Tester or equivalent equipment and a thorough troubleshooting procedure. It is only helpful as a quick and rough predetermination of some possible failure sources.

NOTE: Troubleshooting without a thorough understanding of DME system operation, may lead to misdiagnosis and needless expense. Always review Description and Operation. Description and Operation.

Faults may also be retrieved with the BMW service tester if available. After trouble code diagnosis has been completed, refer to How to Clear Diagnostic Trouble Codes in order to clear the DME trouble code memory. Without - BMW DIAGNOSTIC SYSTEM.

CHECKING THE BASICS
All troubleshooting should begin by "Checking The Basics". Certain basic faults can be undetectable by the self-diagnostic system of the DME control unit and in some cases can actually interfere with the self-checking and fault memory operation.