When replacing control unit of DME/DDE (Digital Motor Electronics/ Digital Diesel Electronics), pleased note the following points:

WARNING: This page is about a different car, the 2002 BMW M Roadster, 2002 BMW M Coupe, 2001 BMW M Roadster, and 2001 BMW M Coupe. However, it is still accessible from the selected car via links, so may be relevant.

Each control unit is programmed with certain basic values, which serve as mean values. The control unit receives different input values, depending on engine condition, which are compared with the stored values. The adaptive system compares the input values with the stored map values. Appropriate correction commands are sent to the concerned drive elements.

If, for example, the DME control unit would be without current for a long time (more than an hour), its adaptive system would lose the stored values. After re-commissioning a cancelled unit or installing a new control unit, the input values of the relevant engine must be read in and stored for the adaptive system.

This procedure could lead to erratic idling and disturbed overrunning of the engine after starting. Depending on the engine it could require some time before all values are adapted to the engine condition.

For this reason, follow the procedure described below before replacing or reinstalling a DME/DDE control unit:

Run engine to operating temperature if possible before replacing the control unit.
Remove control unit, install new control unit and drive vehicle.