Engine ventilation heating

The engine ventilation heating is located at the inlet to the clean air pipe. The engine ventilation heating is optional equipment (SA842 cold-climate version).

The DME control unit activates the engine ventilation heating at terminal 87 (terminal 15 on) via the engine ventilation heating relay thus supplying the engine ventilation heating with terminal 30. The engine ventilation heating relay is located in the power distribution box in the engine compartment.

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)

When the engine is cold, the engine ventilation heating prevents ice formation from freezing condensation within the engine ventilation. If freezing occurs in the engine ventilation system, the pressure in the crankcase may increase. This may cause engine oil to be burnt or pushed past gaskets out of the engine. The oil loss can lead to total destruction of the engine.

Fig 1: Identifying Engine Ventilation Heating Related Components

Courtesy of BMW OF NORTH AMERICA, INC.

The US version features a purge air line for ventilation of the crankcase. The engine ventilation heating systems are controlled directly  by the engine control (not via relay). Observe the wiring diagram in the diagnosis  !