6.2. General information about self-diagnostics of a control system by the Motronic engine
The control unit Motronic systems (computer) has the built-in system of self-diagnostics which defines malfunctions of sensors of system and registers them in memory as codes of mistakes. However, the procedures given in Heads the Power supply system and System of ignition can be used for individual check of components and Motronic system sensors. If it does not allow to find a cause of defect, it is necessary to send the car 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.