6.2. General information about self-diagnostics of a control system of the Motronic engine
The control unit of the Motronic system (computer) has the built-in system of self-diagnostics which defines malfunctions of sensors of system and registers them in memories as codes of mistakes. However, the procedures provided in Heads the Power supply system and System of ignition can be used for individual check of components and sensors of the Motronic system. If it does not allow to find a cause of defect, then the car should be sent to the dealer of BMW who has a necessary diagnostic equipment for reading from the control unit of codes of mistakes.
Further you will have a choice or to make repair independently, or to leave repair to the dealer of BMW.