BMW E38 Webasto auxiliary heater not working
Why does the E38 Webasto switch off after a few minutes or not start?
The cause is often the battery. The Webasto and its blower draw about 10 A, and a weak battery cannot cope: the voltage can drop from 12.9 V to 11.7 V on starting. Charge the battery fully and try again. In the cold the battery charges slowly, so a maintenance charger helps.
Why does the E38 Webasto give a fault code for the auxiliary water pump?
The fault code comes from the auxiliary water pump, so its operation must be checked. Sometimes the pump works, but the cause is in the heating and air conditioning control unit, whose replacement removed the code. Reading the codes requires a battery voltage above 12 V and the MID display in place.
Why does the Webasto start by itself?
The remote control's receiver box may be sending a start signal continuously. The box is behind the rear seat backrest on the front passenger's side. If voltage reaches the Webasto's control wire (pin 1), the fault is in the remote control. If the combustion blower spins as soon as the doors open, the control board is faulty.
How is the E38 Webasto timed?
The heater is controlled through the on-board computer, which has four clock times and an instant start. In a car with navigation the timing is set from the navigation menu, and without navigation with the button marked with a clock symbol. On diesel models, remote start also requires a suitable aftermarket kit; ask a workshop.