Engine ventilation heating: Function

The engine control unit activates the engine ventilation heating (many motorisations via relay).

Switch-on conditions:

• Terminal 15 on
• Ambient temperature less than 2°C
• Less than 360 seconds have elapsed following engine start (time increases depending on engine oil temperature, coolant temperature and driving speed)

The engine ventilation heating works according to the PTC principle (positive temperature coefficient). It consists of electrically heated heating elements. The warmer the heating elements become, the higher their resistance. There is a higher level of current flow when the engine ventilation heating is switched on. With increasing heating, this level of current falls.

The ground connection of the engine ventilation heating is dependent on the motorisation (N20 e.g. via DME). Observe the diagnosis wiring diagram! 

The engine control unit is unable to detect a malfunction in the engine ventilation heating in all versions, as the output has no diagnostic capability (see wiring diagram).

The engine ventilation heating is only fitted with the optional equipment "Cold-climate version", but it can also be retrofitted in individual cases.

We can assume no liability for printing errors or inaccuracies in this document and reserve the right to introduce technical modifications at any time.