Self-diagnosis system and error codes (BMW 5 Series E34)

If a fault occurs in the ignition and fuel injection system while driving, the fault is stored in the control unit as a code. At the same time, the control unit switches to the emergency program so that driving can continue. With the engine switched off, the fault can be recalled from memory using the BMW service tester.

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.

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

Up to 5 defects can be stored in memory. If more defects occur, one of the stored defects is erased.