Fault Accumulator (BMW 3 Series E36)

All DME system variants have emergency modes: If any sensor fails, the control unit uses the average values stored in the unit instead of the signals from the failed sensor. If the air flow meter fails, the control unit uses the throttle position and engine speed as initial parameters for fuel dosing. The transition to this mode occurs automatically and is not indicated to the driver. Driving can continue, and often the deterioration in the vehicle's performance is unnoticeable.

If a malfunction in the ignition and fuel injection system occurs while driving, the defect is stored in the control unit. With the engine off, the defect can be recalled from memory using the BMW service tester, which is connected to the diagnostic connector (on the right in the engine compartment), and eliminated. It is therefore advisable to regularly have the BMW service station interrogate the fault memory, even if it appears that no faults have been detected.

Short circuits, breaks, excess of permissible enrichment values or incomprehensible functioning are stored as defects. In this case, the stored defect can be a failure of an element, corresponding wires or a control unit. In addition, the frequency of occurrence of the stored defect can be output from memory.

The ignition voltage control circuit switches off the DME system when the ignition voltage is low, the engine cannot start. This prevents damage to the catalytic converter.

Caution: When the battery is disconnected or the electronic control unit connector is disconnected, the data in the memory is erased.

Rules for maintaining cleanliness when working with a fuel injection device

Thoroughly clean the connection points and their surroundings with gasoline.

Place removed parts on a clean lining and cover. Use film or paper. Do not use rags with lint! Install only clean parts.

With the system open: If possible, do not work with the compressed air system. If possible, do not move the vehicle.