# Phaeton 2008 auxiliary heater problem 01488



## abooaaishah (Aug 6, 2012)

Hi all,

The car takes its sweet time heating up, takes about 10-15mins to blow nice and warm
relevant codes on VCDS:

01488 - Sensor for coolant temperature; aux. heating (G241)
001 - upper limit exceeded

01207 - Control module for Auxiliary Heater (J364)
004 - no signal/communication - intermittent

really good info here:
http://www.volkspage.net/technik/ssp/ssp/SSP_280_d1.pdf

but couldnt find anyone who's written up a fix for this problem on this forum.
there is a Webasto auxiliary heater sitting behind the front left bumper that i think is the culprit, as it houses this G241 sensor, but really dont know where to go from here.

any guidance is appreciated


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## Prince Ludwig (Mar 24, 2007)

If it's intermittent I'd put my money on damaged wiring between the heater and the HVAC controller.


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## abooaaishah (Aug 6, 2012)

i called my local VW for a price on the unit new
they called me back and said that my car doesnt have the auxiliary heater
my car doesnt have the parking heater option
im rather confused....


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## Prince Ludwig (Mar 24, 2007)

Almost all diesel Phaetons have an auxiliary heater which switches on when the outside temperature is around 5 degrees to heat the cabin up faster. It's located behind the lower nearside bumper.

Further information here and photos here. 

Harry


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## abooaaishah (Aug 6, 2012)

Prince Ludwig said:


> Almost all diesel Phaetons have an auxiliary heater which switches on when the outside temperature is around 5 degrees to heat the cabin up faster. It's located behind the lower nearside bumper.
> 
> Further information here and photos here.
> 
> Harry


yup i thought the diesels had it as well, from what i had already read in this forum
thanks for those links - will have a thorough read after work


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## n968412L (Apr 23, 2009)

I had the same problem with my first Phaeton... the VW dealer swore blind that the car didn't have an auxiliary heater... they were so clueless they couldn't understand the difference between the parking heater factory option and the default auxiliary heater. I did manage to put them straight eventually....


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## Chris Darby (Aug 13, 2014)

On my auxiliary heater the circuit board on the webasto is the controller.
Local VW dealer said it just needed a reset but during the next cold spell the heater came on and I nearly had an electrical fire.
Found that the circuit board was badly corroded. As you might expect the Phaeton webasto has a Phaeton only circuit not available as a replacement. I managed to find a second hand complete unit which has been ok for 2 years . It is quite a job to replace. 

Sent from my Pixel XL using Tapatalk


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## abooaaishah (Aug 6, 2012)

any idea what the part number is for the auxilliary heater?
ill see how much a second hand one costs


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## Tedo (Apr 20, 2015)

If you can still connect to the AUX heater it's an easy fix.
"no signal/communication" error can be due to corrosion of the PCB, connector or wiring. If the AUX still responds, it is not to late to fix this.

G241 - upper limit exceeded can be due to three reasons:
- the most common one: broken circulation pump (when it fails it doesn't show/register as any kind of error)
- broken G241 sensor
- the easy one: air pocket in coolant pipe

How to determine the cause:
- broken circulation pump: use VCDS, open the 18 - aux heater, select component test. When you get to the circulation pump test, stick you head under the car and listen. The operation of the pump is audible. If there is no sound the pump can be broken or the transistor on the PCB failed.
Another way to determine a failed pump or air pocket is by monitoring the G241 value. If the temperature rises really fast when the Webasto starts to heat and overshoots the 90°C value, it means that no water is circulating through the Webasto.
- broken G241 sensor: use VCDS, open the 18 - aux heater, read values of the G241 sensor, when the car is cold. If the temperature reads normal value (value of a cold coolant) than the sensor is ok. If it reads unlikely high or low value... you get the idea...
- if both pump and sensor are OK, you have air pockets in the cooling system or blocked pipe. 

(I'm not fond of installing used stuff as it might be as bad or even worse)


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## dave-c (Mar 8, 2017)

Mine turned to be the circuit board - corroded beyond belief, shorting out and draining the battery overnight.
Replaced the whole unit with a 2nd hand one from a specialist A8/Phaeton breakers near Durham (Eaglescliffe) for a very reasonable £100 or so.
An absolute pig of a job to do though,


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## snapdragon (Aug 8, 2006)

The Aux Heater only fires up at coolant temperatures below 5˚C and it has been warmer than that recently.
Are you having problems with slow warmup above these ambient temperatures?
There is also a plastic inline coolant regulator 4E0121113 next to the gearbox on 3.0TDI models and when it fails, we get a slow warmup as the coolant permanently flows through the thermotop and radiator.

https://www.ebay.co.uk/itm/BRAND-NEW-AUDI-VW-THERMOSTAT-COOLANT-TOPRAN-112-949-4E0121113/


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## kicku (Apr 8, 2018)

Discovering 2 days ago, mine it gave no communication on vcds.
More than this...i didn't know even it has one...:facepalm:
Everything started with a little pool on the driver side front, under fog lamp. Thought will be water that remains under hood from rain or so...until starting the engine i was getting alarm of low level water.
I just cannot understand why webasto ask for almost 1000€ for a new unit...it's just a aluminium piece with a 10€ controller...doh.

I hope the processor will be recoverable on the old pcb...
Anyone of you had experience on change the unit with a used one...it's just a plug & play or what? I was reading on a few topics it's a tricky operation to reprogram the "new" unit.

Thanks for who's replying to me,

(sorry for my poor english )


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## abooaaishah (Aug 6, 2012)

Tedo said:


> If you can still connect to the AUX heater it's an easy fix.
> "no signal/communication" error can be due to corrosion of the PCB, connector or wiring. If the AUX still responds, it is not to late to fix this.
> 
> G241 - upper limit exceeded can be due to three reasons:
> ...


wow! amazing advice i will see if i can follow your instructions and will let you know
my problem was in cold weather car was taking quite some time to blow warm (a good 10 minutes)


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## abooaaishah (Aug 6, 2012)

snapdragon said:


> The Aux Heater only fires up at coolant temperatures below 5˚C and it has been warmer than that recently.
> Are you having problems with slow warmup above these ambient temperatures?
> There is also a plastic inline coolant regulator 4E0121113 next to the gearbox on 3.0TDI models and when it fails, we get a slow warmup as the coolant permanently flows through the thermotop and radiator.
> 
> https://www.ebay.co.uk/itm/BRAND-NEW-AUDI-VW-THERMOSTAT-COOLANT-TOPRAN-112-949-4E0121113/


actually i would say i was getting slow warmup above 5 degress yes


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## abooaaishah (Aug 6, 2012)

Tedo said:


> If you can still connect to the AUX heater it's an easy fix.
> "no signal/communication" error can be due to corrosion of the PCB, connector or wiring. If the AUX still responds, it is not to late to fix this.
> 
> G241 - upper limit exceeded can be due to three reasons:
> ...


Right I followed your instructions 
I tried the component test but couldn't get very far. It just said N/A in each of the four boxes for every test and I couldn't hear the motor when it came to the circulation pump

But I also checked the values. And the temperature reading (group 1) reads a straight 150 degrees with the engine on or off. 

So I assume this is a broken g241 sensor. 

There's another temperature value in block 6 but that reads between 24 and 26 degrees. 

What do I do now? Where is this sensor?


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