Diagnosis of the DAB tuner

• DAB tuner in external control unit:  Before diagnosing the DAB tuner, the voltage supplies and bus communication must be safeguarded. If the bus communication is working and no internal control unit faults of the DAB tuner are stored, the aerials must be checked in the event of a customer complaint.
• DAB tuner integrated in the headunit:  In the current headunits (radio/Car Information Computer/multimedia platform), the digital radio function is being integrated into the headunit little by little. In this case, a separate DAB control unit is no longer installed in the vehicle. The function of the DAB unit is taken over by the headunit in this case. For the case where the DAB tuner is integrated into the headunit, the aerials for receiving the digital signal are connected to the headunit.

Depending on the operating status, a certain quantity of exhaust gas is returned via the EGR valves into the intake area in order to reduce pollutant emission.