Evening guys ,

I’ve got to replace the thermostat on my A3 2.0 TDI . Anyone know which brand is the original ? I’m thinking of fitting  a Febi stat , any opinions on this brand .

 

Thanks and merry Xmas

Hello Andy, 

There will be varying opinions on the use of genuine VAG parts or aftermarket, in terms of what I would call critical applications.

One way of looking at it is that if you are DIYing it, then your labour is free, so you can invest the savings by buying ‘genuine’ parts. 
Re. Febi:-  I have used this aftermarket brand to good avail with a number of applications - however, not including a thermostat renewal, where I used a VAG part at discount. 
If you wish to buy Febi to save some funds, then it might be worth trying Car Parts in Motion. I have found them to be competitive and efficient. No connections, and there are many others inc. those who offer large discounts on so called retail prices, and you still end up paying more that you would with competitors! 
Perhaps you could let us know what you decide Andy.

Kind regards,

Gareth. 

Thanks for the reply Gareth,

 

I would rather use genuine VAG tbh . Any idea of the cost ? I will be doing it myself . Do you know if it’s possible to replace without removing the alternator ?
 

Thanks Andy

Hello Andy,

For VAG parts, you could try Audi Parts Direct at Cardiff ( part of now Mon Motors- previously Cardiff Audi) or Aberdeen Audi. Both were giving a bit of discount on mail order. Current cost?? - with everything rising in price at a rate of knots. 
I didn’t remove the alternator on my 1.6. One bolt was awkward as I recall, but…. Don’t forget to order a rubber ‘gasket’ since it was a separate part with mine. This gasket was daftly priced for wat it was - from memory.

Kind regards,

Gareth. 

I’ve used Febi on numerous occasions and rate them . Anyone know on the 2.0 TDI if it’s possible to change without removing the alternator ? 
 

Thabks chaps

Now it’s stop raining I’ve managed to have a good look at the thermostat location . It appears if the throttle body is removed it will give good access and the alternator can remain . Any words of wisdom before I start would be much appreciated.

 

Rgds Andy

Quick update on this . It’s a pig of a job !! Removed alternator and air con pump to gain access . Maybe easier removing inlet manifold and throttle body but will need a new gasket if you go down that route . I’ll update when we have it back together if it cures the problem . As per Gareth’s advice you do indeed require an extra gasket . Thank you Gareth 👍

Edited January 25, 20233 yr by Spock

They can be a nightmare to change. I know on my A6 c5 the front has to come off. 

Pleased to report its all back together and the needle is sitting nicely at 90!
Thanks for your contributions chaps 

22 hours ago, Spock said:

Pleased to report its all back together and the needle is sitting nicely at 90!
Thanks for your contributions chaps 

Glad you got sorted 🙂

Bit of an old thread but I am about to do the same job.

I've just ordered a genuine thermostat from the dealer but unsure if I need this extra 'gasket' as they didn't seem to know. Is it just the big o ring that sits on the thermostat? 

Also, whats the best way to get into it? Is it and alternator out job or take off the manifold? Any help and tips appreciated. 

Cheers 

Hi ,

 

it should come with the large o ring . It’s the smaller one on the side that I purchased separately. I replaced this and it leaked so just use the old one and put some sealer round it ! I did it on a ramp from below . It’s a pig of a job ! Removing the manifold may be easier ! Good luck 

Welcome Pip, 

You will need a new O ring. 
Alternator out or not ?? On my earlier A3 - no. 
Regards,

Gareth. 

Thanks guys.

Just picked up my new thermostat from the dealers. It has the big o ring on but I'm unsure where there's meant to be another one? Does anyone have a link or picture for the other gasket/o ring that is needed? 

Going to tackle it on the weekend. I think I'm going to remove the manifold and go that way so wish me luck lol. Cheers 

Hello Pip,

I think (in caps) there is only one O ring, and that wasn’t supplied with the one for my 2006 1.6, so it seems you are lucky!
More than one needed? Proof positive is to ring the Parts Section at the dealer you bought it from, and they will confirm/ refute. 

Regards,

Gareth. 
Next best option would be to look up LLL Parts website. 

Hi , there is a pipe that slides in from the right . From memory the seal is approx 25mm diameter and approx 10mm width . I replaced it with a genuine one about £9 ( rip off ) and it leaked !!! Another couple of hours to strip back down . Use the old one and apply an appropriate sealer . We put the old one back on With sealer and 30k later still going strong . If you remove the manifold you will probably need a new gasket for that . I think manifold removal would be the easiest way to do it or take it to the garage that’s even easier 😂

On 12/4/2025 at 9:17 AM, Spock said:

Hi , there is a pipe that slides in from the right . From memory the seal is approx 25mm diameter and approx 10mm width . I replaced it with a genuine one about £9 ( rip off ) and it leaked !!! Another couple of hours to strip back down . Use the old one and apply an appropriate sealer . We put the old one back on With sealer and 30k later still going strong . If you remove the manifold you will probably need a new gasket for that . I think manifold removal would be the easiest way to do it or take it to the garage that’s even easier 😂

Cheers guys. 

Had a look on LLL parts and found this diagram of the thermostat (cheers Gareth). It only shows the one o ring so a little bit stumped there.

What sort of sealer did you use on the old gasket? Just incase I have to do the same haha.