Auxiliary Cabin Heater: Description and Operation

Coolant auxiliary heater

Thanks to its high efficiency, the 1.9-liter TDI engine with pump injection system develops so little heat that sufficient heat output may not be available in certain circumstances.
In countries with cold climates, an electrical auxiliary heater is used to heat the coolant at low temperatures.
The coolant auxiliary heater is comprised of three Glow Plugs (Coolant) Q7. They are installed to the coolant connection on the cylinder head.
The Diesel Direct Fuel Injection Engine Control Module J248 uses the coolant auxiliary heater signal to activate the relays for low and high heat output.





Either one, two, or all three Glow Plugs (Coolant) Q7 are switched on depending on the available capacity of the three-phase AC generator.