4.2 Tdi Auxiliary Heater
 

Hi,

My Auxilliary heater seems to be running still after an hours driving. Is this ok? It seems to me that it is using fuel unnecessarily.

Is there a way to change the settings? I can't find anything in MMI

Thanks

Jon

i dont think my one works:Confused:

It should be automatic, so there are no settings, and I see no reason at all why it would be running.

Stupid question, but it is definitely the webasto chugging away, and not the suspension air compressor or something else over running ?

Have you run VCDS against it to check for errors ?

Yep definitely coming from the Aux heater exhaust, front drivers side just in front of the front suspension mounts

You can override the usual automatic temperature based activation by using the Auxiliary Heating menu in the AC part of the MMI. Could it be that it is constantly set to on? Do you have a little flashing heater icon on the main dash display by the time by the rev counter (I think?). Otherwise could be a faulty temperature sensor as it is set to come on under 5 degrees and as long as your low fuel light/warning is not on.

Thanks for your reply. I don't have any control under the AC menu on the MMI.

I am in the process of getting VAGCOM I'll know more then.

Seems like a sensor out though doesnt it.

Anyone know a part number or cost?

Thanks

Do you have the ' set up ' button on the climate control , there's an option in there for aux heating on or off

The Webasto coolant heater was fitted to all D3 A8 diesels, and the Q7 4L also.

And the A2 diesel, and likely some others.

It is designed to bring the engine up to temp rapidly rather than waiting for the diesel block to eventually do its thing. It shouldn't need to run for more than about 10/15 mins really.

Optionally, although not available in the UK brochures, you could get auxiliary heating which uses the same webasto heater, but has a second battery and water pump to allow the car to pre heat with the engine off. This has the setting in the MMI and usually a remote control also. Retrofitting this to warm up with the engine off isn't particularly hard. You can enable the controls in the MMI with vagcom, but without the pump to move the water round the heater will just boil the water and shut itself down due to overheating.

Jon, I would assume, has a standard UK spec car, with no Aux heating, but will have the Webasto heater as standard, and it is this which is over-running.

Interestingly, they often fail to work, but over running is not something I've heard of. Either way, there's no MMI config to it (unless someone has been fiddling).

So, I guess the heater thinks the coolant is below desired temperature which is why it is still running making a sensor a reasonable bet. You've not mentioned, so I assume the car is getting up to and maintaining 90 on the temp gauge ?

Vagcom should be able to tell you a lot, and ever if there are no errors, the measuring blocks should be able to tell you what temperature the webasto thinks the coolant is at....

Thanks. Yep thats right.

Car sits at 90 no problem in all conditions and down to -4 we had last week.

Once I've got the VAGCOM I'll let you know.

Cheers

Jon