Mercedes-Benz A-Class Operator's Manual page 452

450 Display messages and warning/indicator lamps
Display messages Possible causes/consequences and
* The radar sensor system is malfunctioning. Possible causes are:
Currently Unavailable
Radar Sensors Dirty
Soiling of the sensors
R
Heavy rain
R
Extended country driving without other traffic, e.g. in the desert
R
Driving systems and driving safety systems may be malfunctioning or temporarily unavailable.
Once the cause of the problem is no longer present, driving systems and driving safety systems will be available
again.
If the display message does not disappear:
Pull over and stop the vehicle safely as soon as possible, paying attention to road and traffic conditions.
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Clean all sensors .
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Restart the engine.
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M M Solutions