Thanks for the links Kev. 

Annoyingly last week I discovered from my mechanic that if I buy any 2.5tdi engine and keep my current injection pump and ECU the car will think the replacement engine is the original and will run. Wish I'd known that a year ago instead of worrying about coding of injection pumps and imobilisers etc. 

So my simplest option is to find a bau version of the 2.5tdi as this was the last variation of that engine and most refined in theory. Trying to find one with low miles and proven service history, but naturally this is proving difficult. 

Hi Steve, just wondering how this all played out and whether you were able to save your car? I was in a similar situation with mine but due to a rotted back axle MOT failure, my mechanic (who's a trusted friend) advised me that a decent axle would be difficult to find due to the age and the best course of action would be to scrap and/or break the car for spares. Anyway, I managed to find a remanufactured axle in Poland that'll probably outlive me and after about £1800 for the axle, shipping, front suspension rebuild (needed to be done) and labour the car is getting down the road well good for another few tours of duty. My mechanic mate tried to talk me out of it as he didn't think it made financial sense but the rest of the car is sound, the wife and kids love it, and it does everything I need it to do perfectly and in style. The point of all this is to say that if it makes you happy and you can afford to do it then just follow your heart, I'm glad I did.Audi A6 C5

4 hours ago, daveyboy1967 said:

Hi Steve, just wondering how this all played out and whether you were able to save your car? I was in a similar situation with mine but due to a rotted back axle MOT failure, my mechanic (who's a trusted friend) advised me that a decent axle would be difficult to find due to the age and the best course of action would be to scrap and/or break the car for spares. Anyway, I managed to find a remanufactured axle in Poland that'll probably outlive me and after about £1800 for the axle, shipping, front suspension rebuild (needed to be done) and labour the car is getting down the road well good for another few tours of duty. My mechanic mate tried to talk me out of it as he didn't think it made financial sense but the rest of the car is sound, the wife and kids love it, and it does everything I need it to do perfectly and in style. The point of all this is to say that if it makes you happy and you can afford to do it then just follow your heart, I'm glad I did.Audi A6 C5

The poor car is sat on my drive. I just cannot find someone who is experienced with the coding. As no one can give me a clear answer if any 2.5tdi will fire up with my ECU etc. finding a second hand engine is difficult. Finding one with service history that hasn't got any issues. 

Again I've thought about buying a donor car and having the engine, ecu and injection pump transferred to mine but keeping my instrument cluster but again finding someone to do the coding is proving problematic. 

I did think of doing an engine swap from a different car but this did not go down too well with my dad who was the original owner. Hos view was an Audi should have an Audi engine. 

It upsets me seeing it the way it us and would love it back on the road. 

Hi, Just wondering if you made a decision on the car. I also have an A6 C5 Avant with a 2.5 tdi engine. It has covered 314K miles but needs some attention I got the car at 3 years old with 38k on the clock so I have had great use out of it. The car is based in Scotland so corrosion is the enemy. The engine has been out twice, both times to sort the top end.

I am with your Dad, an Audi should have an Audi engine. In you situation I would be tempted to get a donor car with a running engine of the same type. I would then make sure that there are no leaks or noises then check the compression and put a borescope into the combustion chamber.

I just bought an Allroad last week which is 2 years newer and has 90k on the clock but after buying it I am now more determined to keep my original car on the road.

On 2/4/2025 at 12:36 PM, A6 C5 Avant owner said:

Hi, Just wondering if you made a decision on the car. I also have an A6 C5 Avant with a 2.5 tdi engine. It has covered 314K miles but needs some attention I got the car at 3 years old with 38k on the clock so I have had great use out of it. The car is based in Scotland so corrosion is the enemy. The engine has been out twice, both times to sort the top end.

I am with your Dad, an Audi should have an Audi engine. In you situation I would be tempted to get a donor car with a running engine of the same type. I would then make sure that there are no leaks or noises then check the compression and put a borescope into the combustion chamber.

I just bought an Allroad last week which is 2 years newer and has 90k on the clock but after buying it I am now more determined to keep my original car on the road.

Apologies I've only just seen this. I still have the A6 but no further forward to be honest. 

They definitely become a labour of love. The issue I've found with the 2.5tdi V6 is parts availablity for the engine now. 

How are you getting on with yours?