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Ridley Scott

Definitive Guide to Installing Auxiliary Heating to your A8 D3

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After purchasing a 2008 4.2Tdi Sport early on this year, the option that I did miss, which I fitted to my E39 BMW, was the ability to remotely operate the Auxiliary Heater to defrost the windscreen and take the chill out of the air in the cabin. So I set about looking into retrofitting this to my A8 which turned out to be not as simple as it did with the BM.

Since Audi dropped the ‘Parking Heater’ from the options list around 2006 (Due to U.K. Emissions technicality) all you had fitted to all Diesel A8’s was a Basic Webasto Fuel Burning Heater (FBH) which only assisted in bringing the engine up to temperature in cold weather as the Diesels run a lot cooler than there Petrol counterparts.

So after doing quite a bit of homework via various forums and ETKA I found out what I needed was to fit an additional Recirculation Coolant Pump (V55) to the heater, various pipe work & a Receiver to accept the Remote Control Signal. The Pump was necessary to pump the coolant via the heater when the Engine was switched off. As this was the engines coolant pump job when it was running.

The cost of this project will be around £220-240 depending on what you can source the Remote kit & Pump of E-Bay. The other items I used Trade Parts Specialists and Mellor Auto Electrical, all parts need to be genuine to correspond with the factory fit.

Now bear this in mind, this will take the chill out of the cabin and defrost the windscreen, as well as pre-heat the engine. It will NOT warm the interior as if the engine has been running for 10 miles. To get the interior warmer you have to fit a Shut-Off Valve (N279) which diverts the coolant away from the engine and around the cabin circuit after being pre-heated in the FBH, this is a big task on the A8 and as this is not what I required as I was wanting to prolong the life of the engine (Pre-heating the engine leads to less wear) this option was not only cheaper but a lot easier to fit.

Before we start you can opt out of the remote kit and have the heater start via the timers on the MMI A/C Set up menu thus reducing costs but in practice I can assure you that the remote function is well worth the money

Right, if your still interested here we go. Parts needed are as follows:-


Webasto T91 Telestart VW Audi Seat (Try to obtain the one from Car System, Poland as they sell it with the Genuine Audi Fob)

Webasto 12 Volt U4847 Recirculation Pump (V55) (make sure it has the cable attached, not a socket) + Pump Clamp.

Trade Part Specialists:-

FAKRA 2M Aerial wire 000 0998 653

Hose 4E0265055

Hose 4E0265057

4X Spring Band Clamps N 906 870 01

Mellor Auto Electrical, Ossett:-

Webasto Axial Water Pump Housing 93012C

Straight Plastic 20mm Water Connection Pipe


You also need to access the ECU via VAG-COM

First of all you need to get the car as high as you can using sturdy axle stands, remove the front wheels (fig 1) then the under tray, inner wheel liners (fig 2) followed by the bumper.


Fig 1


Fig 2

Once this is done you have to remove the Off Side Front Air Filter Housing & Head Light which gives you access to the Webasto FBH, next remove the FBH Exhaust (fig 3), Then using brake pipe clamps restrict the coolant hoses feeding the unit (this saves dropping the coolant) unclip the hoses & electrical connectors then remove the FBH.


Fig 3 Fig 3

Next we need to swap the Stock Water Pump Housing with the Axial Housing paying close attention to orientation (fig 4) then mount it and the hoses to the FBH (good idea to run a Tap down the thread to clean it out before attaching the clamp).Fig 5,6 & 7


Fig 445036-definitive-guide-installing-auxiliary-heating-your-a8-d3-dsc_0028.jpg

Fig 5


Fig 6


Fig 7

Plug the Pump into the FBH by removing the blank on the second socket on top of the FBH accessed under the cover adjacent to the Main Harness sockets.


Reinstall the FBH and re-route the coolant hose around the front, the original hose does re-route, quite tricky but it does (make extra sure you don‘t kink the hose, causing a restriction). Once done add a tie-rap to keep the hose from the sharp frame edge.




IMPORTANT Before you plug the main connector back into the FBH you need to introduce a wire to Pin 1 of the main plug, the wire has to be long enough to be routed to the boot/trunk area for the Remote control receiver.

Once this is complete rebuild the front end and route the remote cable adjacent to the bonnet seal around to the coolant header tank.

The next step is to route the receiver wire to the boot area which requires you to remove the CD Changer & Audi Music Interface Dock & Glove box and in the engine compartment remove the panels which surround the Pollen Filter & Header Tank, this exposes a rubber bulk head grommet to which you can feed the wire thru.

Now I ran the cable along the sills into the rear trunk area by removing the sills, rear seat base and then the panels/carpets in the boot. Whilst these are removed you can then feed the Fakra Aerial cable (by means of removing the C post panel & grab Handle) to the top of the rear window where you will find a spare socket on the Rear Window Aerial Control Unit to plug the cable into.

Once this is done grab a live to power up your Receiver (I used the live from the rear of the Aux Power Socket) , fit that and reinstall everything.

The last step is to Code the Controllers via VAG-COM

0.Turn ON ignition.

1.Connect VAG-Com cable to car port underneath the dash.

2.Open VCD application on PC.

3.Select "Auto-Scan"

4.Select "Gateway Installation List"

5.From the list of devices select "08-Auto HVAC"

6.You will see the list of faults on the screen related to the Climatronic control unit if any.

7.Press "Done, Go back"

8.Select "Coding", the first button from right to left on the first row.

9.To the code written in the upper first box add 2.

10.Click "SAVE"

11.You will get the message "Coding accepted"

12.Close the VCDS application.

13.Turn OFF ignition

14.Turn ON ignition again.

15.Check the Climatronic menu on the MMI to notice the differences.

This informs the Climate Control Unit that it has Auxiliary Heating as an option and you will find that it is accessed thru the Setup Menu with various ways of enabling it either directly or timed.

The next step is go back into the VCD Application and locate Module 18 (Aux Heating), select Adaptation - 10 on the Advanced Functions, scroll to Channel 10, the stored factory value should be “00000” this needs to changed to “00003” and Saved.

What this enables is the Activation of the Recirculation Pump (V55) when the FBH is operating to pump the coolant around the system whilst the engine is off.

Right, all is done, take into consideration that you have to have a healthy battery to operate the Auxiliary heating, if the Power Management Control Unit censes the Battery Volts falling below 11.75 Volts it will shut down the operation and like wise the fuel level, if your Amber Fuel Reserve light is illuminated this will also shut down the system and if both criteria’s are not met in the first place it will not even commence the operation.

I personally have quite a long distance to travel daily so that gives the battery a healthy charge so I can set my timer to activate the Auxiliary Heater for 45 minutes, if you only travel short distances you need to take this into consideration before you even fit the unit as I have heard stories of others having this problem and it of eventually being of no use as they only travel very short distances allowing an insufficient charge.

One last piece of advice is to turn up your Temperature to HI before you leave the vehicle overnight, as I still have not found a Adaptation Channel which turns up the Heat when Auxiliary Heating is activated














Edited by Ridley Scott

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Thanks for posting this I was only looking last night to see if it was possible – It looks like you’ve done your homework!. TBH it all looks a little complicated for my mechanical abilities. Previous posts had suggested that it was possible with just a VAG-COM change

If I just want it to take the chill off in the winter and deice the windows do I need to get the spanners out or will the VAG-COM work?

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I did mine via VCDS and the MMI hidden menu, and the webasto comes on with the timer but doesn't really seem to heat anything other than itself.

After reading this excellent post and photos, I can see why.

Of note, I'm sure my climate control does switch to HI unlike the original poster's (as I happened to note this upon the first test run), but I will check.

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Thanks. You need to fit the Recirculation Pump because this provies the flow of coolant thru the Auxilary Heater/Climate Circuit, if not after a couple of minutes it senses the water overheating and shuts down.

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Thanks guys - Found this really useful and have forwarded to a heater fitter who is looking at pulling together some prices for me.

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Excellent write up, and many thanks for sharing the information +++

I know you said that you wanted the engine pre-heat option, but did you do much investigation into how difficult fitting the shut off valve (N279) would be?



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Sorry for not replying sooner. To install the shut off valve requires you to interfere with the plumbing of the heater behind the engine bulkhead, which looks like too much work, which is why thank god it's not what I wanted.

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Address 08: Auto HVAC Labels: None

Part No SW: 4E0 910 043 B HW: 4E0 820 043 D

Component: KLIMAAUTOMAT 016 0400

Revision: 00000030 Serial number: 00000000082085

Coding: 0084051

Shop #: WSC 02311 785 00200


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i have done this upgrade in end of november last year and must say it works well, however you will soon know if youve got a duff battery as i did lol.

i also didnt install the shut off valve as its to much work................ i did manage to slow the fan speed with vag-com and that helps the battery alot :)

the missis loves it....... i havent done the remote control yet (pin 1 add wire) and just use the installed mmi timers etc but all works well

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There are 2 different t91 kits on the site :

Audi Telestart T91 KIT
Reception range up to 1.000 meteres.  Compatible with Webasto heaters  :

Thermo Top E,Thermo Top C, Thermo Top P, Thermo Top V     and systems with Timer 1533


Audi Telestart T91 KIT
Succesor - 1K0963513A and 4F0909509


Which one works?


Thank you

Edited by TrollTor

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