See also:

Problems with the rear window defroster
The rear window defroster has deactivated itself prematurely or cannot be activated. •► Switch off any consumers that are not required, e.g. reading lamps or interior lighting. When the ...

High outside temperatures
If DEF heats up to over 122 °F (50 °C ) for extended periods, e.g. as a result of direct sunlight on the DEF reservoir, DEF can decompose. Ammonia vapors develop as a result. WARNING When o ...

General notes
WARNING All categories of messages contain important information which should be taken note of and, where a malfunction is indicated, addressed as soon as possible at an authorized Mercedes ...