Big Car Club - MPV and SUV Forums

Here is my problem.  The aux heater continues to run when the engine coolant temperature is at 90 degrees.  After an hour plus ride - engine temp right at 90 for at least 45 minutes - when I pull into the garage - the fan on the aux heater is running after I shut down.

I was under the impression that the engine coolant temperature sensor controlled the heater on and off  (in conjunction with the outside temp sensor under the wiper motor).  My run on pump is not working, but I don't see how that affects this problem.

I will check with VAG-COM tomorrow - but as the heater is working, I am not sure what that will tell me.
Any thoughts are appreciated.

Thanks,

The aux heater has temp sensors on it which should switch it on and off, in vagcom look at live data with it running and see what temps its recording.

my old mk1 did this also,  i cured it by unplugging the sensor and running 2 wires to a 2nd heated windscreen switch i got from ebay,  i wired this up to the heater and lighting circuit and it looked like a factory for job,  then you can switch on or off the heater when you wish .

Hi All,
As far as I know and I'm pretty sure, the auxillary heater does stay on once activated. Even when the engine is up to temperature it will continue until the ignition is turned off and even then takes a few minuitesfor thejet noise to wind down.
The thing that does surprise me is that usually when your auxillary water pump is not working the auxillary heater cuts out after a few mins because the heater overheats due to the water not circulating. After it has done this a few times it logs a fault code and will not start up again until the fault code is erased.
                           Steve