I have a 2021 Audi A4 Avant 40TDI bought from new, as I retired early and wanted to ensure I had a good car from scratch to last me as long as possible. I've done 52,000 miles (approx. 13,000 per year) of mixed distance trips, mainly A roads dual carriageways and motorways, and not just short local trips. I'm not a slow driver, I tend to push the car wherever it's safe and possible to do so.  Paid for extended Audi warranty at the end of year 3, including a deal on services and on MOT's. Car has been serviced promptly and regularly  in complete accordance with the servicing conditions.

Yellow Engine management came on about a month ago, been in and out of the Audi local main dealer. Today told it's a DPF failure, 'probably' caused by 'driving style', and the warranty does NOT cover DPF. Quoted £6,500...

Driving style explained as too many short trips and not driving fast enough. When I disputed I was told they couldn't discuss that any further as it was 'obvious to them' that this must be the cause. I asked about 13,000 miles saying 250 miles a week is a heck of a lot of short trips!, their computer management systems, the regular servicing checks they should have done over the last 4 years, and  with them giving me no previous warning etc. Silence.

Can't really afford to pay £6,500 - car book value is circa 22k so £6,500 almost a third of its value. I'd have to get it fixed to be able to sell it. Rock and a hard place!

Anyone else facing the shocking realisation: that buying a new Audi, driving it properly and getting it serviced regularly and in accordance with the servicing requirements at 'expensive' dealership service charges to ensure no issues in maintaining the warranty, ends up with Audi just looking to rinse you further. 

Very disappointed and disillusioned with Audi.

Any advice gratefully received

Surely it's made of gold. There are companies that clean them or alternatively find either an Audi or DPF specialist and try them. I didn't take out Audi's warranty/servicing/ MOT combinations because I see them as a cheap loss leader so they can screw you on consumables like brake pads/discs etc. 

Getting this done elsewhere might affect the warranty for things affected by the DPF (if any) but at that price in my opinion it's worth the risk.

Thanks Kevin. Yes it must be gold (!) - the dealer said the replacement DPF unit was £3,500, and when I queried how long it would take to fit they said 8 hours - so I then queried  £3,000 for 8 hours (?!) and they said there are other things that also have to be replaced like sensors and hoses, and a computer reset etc. 

The dealer rang me  first thing this morning and said they could 'help' by reducing the cost to £5,200 - so £1,300 off 'to help' - which is a start, but £5 grand is still unaffordable for me. I wonder if it's because I told them I would have to try and find another solution and took the car back off them.

Off to see an independent Audi specialist today. Spoke to them on the phone yesterday and they said a clean might work, but they would review, test and then discuss it with me. I've also been told by someone else that I could consider a 'remap' - whatever that means. I'll try the specialist first and see what they say.

Watch this space... 

Please keep us posted on how you get on. An alternative option would be to get the car remapped and have the dog mapped out. 

The fact they can knock off £1300 immediately shows how much they try to overcharge.

They wanted £208 for a sunroof service and I got it done for £60 at a specialist near Newcastle. Swift Moror Engineering in case anyone is interested.

8 hours ago, milfordnige said:

Thanks Kevin. Yes it must be gold (!) - the dealer said the replacement DPF unit was £3,500, and when I queried how long it would take to fit they said 8 hours - so I then queried  £3,000 for 8 hours (?!) and they said there are other things that also have to be replaced like sensors and hoses, and a computer reset etc. 

The dealer rang me  first thing this morning and said they could 'help' by reducing the cost to £5,200 - so £1,300 off 'to help' - which is a start, but £5 grand is still unaffordable for me. I wonder if it's because I told them I would have to try and find another solution and took the car back off them.

Off to see an independent Audi specialist today. Spoke to them on the phone yesterday and they said a clean might work, but they would review, test and then discuss it with me. I've also been told by someone else that I could consider a 'remap' - whatever that means. I'll try the specialist first and see what they say.

Watch this space... 

Hi it is not your driving style, its a future fault the car had when it rolled off the line, my money is on the code being P2002 low pressure EGR cooler blocked this is described as DPF bank 1 particle filter below threshold, you do not need a new DPF just the cooler and its valve, as for remaps an elder statesman of this forum said we have more remaps on this forum than the ordinance survey, they are never any good.

Steve.

Just wondering where you are up to with this one? Seems very unlucky at only 52k miles. Hopefully you get some joy with cleaning it out. If you do - I can and for future maintenance, I highly recommend Archoil AR6400-D. Its a DPF cleaner with very strong detergents in, design to be used roughly every 5000 miles (it also does your turbo and cat). Many people have found this gets rid of the warning lights all together.

I use it in my 40TDI Quattro on 54.5k miles, which feels much better post usage (uptake, smoother etc). I also use Archoil AR6900-D which boosts cetene and cleans as well.

 

Just a thought!

Thanks for your advice. I took it back

from the dealer to explore some other options. I booked it into a local independent specialist garage (not a dealer) for last Monday 13th October - there was a long waiting list. 4 days before the engine management light went off! I took it to the specialist anyway, and he confirmed it was a DPF fault code on the system, but he reckoned it had regenerated. In fairness he didn’t charge me but he said it was unusual to have the yellow light on for that many weeks given the mileage and type of driving I do. He suggested I just monitor it and in fairness didn’t charge me anything.

It’s not reappeared to date. What was really interesting was when I asked him what sort of price he’d be looking at to replace the DPF with a genuine Audi part. He said ‘I’m sorry it will be expensive, around £1,500 or perhaps a little more if sensors need replacing too.’!

That’s still painful, but compared to the dealer’s starting point of £6,300 and second ‘discounted price’ of £5,200 it’s more acceptable. He laughed when I said I’d heard the filter itself was £3,500 and said no, it’s not, who ever told you that! I didn’t say it was the dealer…

I’ll give the cleaner a try though, belt and braces

Thanks again

55 minutes ago, milfordnige said:

Thanks for your advice. I took it back

from the dealer to explore some other options. I booked it into a local independent specialist garage (not a dealer) for last Monday 13th October - there was a long waiting list. 4 days before the engine management light went off! I took it to the specialist anyway, and he confirmed it was a DPF fault code on the system, but he reckoned it had regenerated. In fairness he didn’t charge me but he said it was unusual to have the yellow light on for that many weeks given the mileage and type of driving I do. He suggested I just monitor it and in fairness didn’t charge me anything.

It’s not reappeared to date. What was really interesting was when I asked him what sort of price he’d be looking at to replace the DPF with a genuine Audi part. He said ‘I’m sorry it will be expensive, around £1,500 or perhaps a little more if sensors need replacing too.’!

That’s still painful, but compared to the dealer’s starting point of £6,300 and second ‘discounted price’ of £5,200 it’s more acceptable. He laughed when I said I’d heard the filter itself was £3,500 and said no, it’s not, who ever told you that! I didn’t say it was the dealer…

I’ll give the cleaner a try though, belt and braces

Thanks again

Good news! It does seem Audi were taking the Micky. £1500 is a lot more palatable than £5k 😅 

Definitely worth some preventative maintenance. I also started using Winns Adblue crystallisation treatment as well.

All this emissions gubbins creates a bit of a headache so I figure anything that can be done to offset an expensive bill is worthwhile. 
 

Like you, I plan on keeping the car for a long time (even as a second car down the line). 

Edited October 20, 2025Oct 20 by A4EverQuattro

1 hour ago, milfordnige said:

Thanks for your advice. I took it back

from the dealer to explore some other options. I booked it into a local independent specialist garage (not a dealer) for last Monday 13th October - there was a long waiting list. 4 days before the engine management light went off! I took it to the specialist anyway, and he confirmed it was a DPF fault code on the system, but he reckoned it had regenerated. In fairness he didn’t charge me but he said it was unusual to have the yellow light on for that many weeks given the mileage and type of driving I do. He suggested I just monitor it and in fairness didn’t charge me anything.

It’s not reappeared to date. What was really interesting was when I asked him what sort of price he’d be looking at to replace the DPF with a genuine Audi part. He said ‘I’m sorry it will be expensive, around £1,500 or perhaps a little more if sensors need replacing too.’!

That’s still painful, but compared to the dealer’s starting point of £6,300 and second ‘discounted price’ of £5,200 it’s more acceptable. He laughed when I said I’d heard the filter itself was £3,500 and said no, it’s not, who ever told you that! I didn’t say it was the dealer…

I’ll give the cleaner a try though, belt and braces

Thanks again

Hi try running the car with Dipetane, I use it and its much cheaper on eBay, say £21.50 for two litres and seems to work better than Archoil which is about £26.00 a litre its very good for cars that only do short journeys like my cab, because its a hydrocarbon it makes the soot particles smaller therefore they burn off at a lower temperature, goole it.

Steve.

33 minutes ago, Stevey Y said:

Hi try running the car with Dipetane, I use it and its much cheaper on eBay, say £21.50 for two litres and seems to work better than Archoil which is about £26.00 a litre its very good for cars that only do short journeys like my cab, because its a hydrocarbon it makes the soot particles smaller therefore they burn off at a lower temperature, goole it.

Steve.

Doesn’t AR6400-D chemically clean where as Dipetane is a combustion enhancer and doesn’t really ‘clean’ per se. For cars already a bit clogged it seems AR6400D-d is the better choice? It also cleans the turbo and cat. 
 

AR6400-D is also only used twice a year dependant on mileage. The 6900-D is a different kettle of fish all together, it boosts Cetene levels as well as clean and is an every tank of fuel thing. I use both for the same reason as you, lots of short trips. 
 

Each to their own though 👍

p.s I do like the mpg increase  claims though. Archoil do state improved mpg but looking at reviews in the site some people claim 10mpg increase which is a lot!

Edited October 20, 2025Oct 20 by A4EverQuattro

So here's the latest update on my sorry tale.  Worth saying at the start that I've recently spent £13 on an OBD bluetooth diagnostic scanner to try and work out a problem on my wife's Mazda MX5, and found it also works on the Audi. More on that later.

To recap, the engine fault yellow light went on late in August, the dealer said the DPF had to be replaced and wanted £6,500 (a day later they called me and 'reduced' it to £5,200). They insisted it wasn't covered by my extended warranty, and was due to my 'driving style', of short local trips (and probably assuming I was a slow driver based on my age). Wrong on both counts. I said I'd think about replacement and took the car home.

I booked to see an independent garage and the week before my appointment the light went off - 7 October. The garage advice was to just keep an eye on it. The independent garage told me they had left the fault code on the car, but that there were no errors on the system from any of my previous visits to the dealer, so these must have been cleared by the dealer before I collected the car. The independent didn't give me the fault code, and I wasn't clued up enough at that point to ask for it.

The fault light came back on 3 December. The light went off on 15 December

In all this time there has been no loss of performance at all and fuel efficiency is normal. However I have started to notice sooting around the exhaust outlet.

Service light came up on the car recently, so I took it to the independent garage for a service on 3 February. Collected the car and was told they had concluded the DPF was faulty and needs to be replaced. They apologised and said their initial advice on £1,500-2,000  estimate was way-off, they had just got a quote for the part which was £4,000 alone and their guess was a full day's work which would be around another £1,000 - so not too different to my dealer's final 'offer' of £5,200 back in September. It just seems so wrong on a car of only 55,000 miles and less than 5 years old. It's not fit for purpose as I see it, but I can't see how I can prove this. The independent garage also said thy can get this £4,000 replacement part immediately off the shelf, and they think that says Audi know these things fail prematurely because that's a high cost item to be sitting on a shelf.

Today, 6 February, the fault light came on again. My cheap OBD scanner says it's a P226D code and describes this as 'deteriorated, damaged or has a missing substrate'. Googling this it seems most likely it could be cracked - so could that have happened due to too much sooting? Or equally could the part just have been faulty due to manufacture...  It seems to me that it will be difficult/impossible to prove and easy for Audi to say 'its been caused by driving style'. 

As I said before, I have an extended warranty, but on checking this specifically excludes the DPF...I think they know don't they...

It seems I've made a big mistake in buying a new Audi diesel. I'm going to write to Audi to complain but I don't hold out any hope. It would be interesting though to know how common this is, and if there are a lot of issues, try and see if a class action could be brought. Won't help me but might help others.

 

 

 

 

 

 

That’s very unfortunate. I feel your pain, especially on a car doing pretty average mileage, purchased from new and serviced.

Unfortunately modern diesels have the odds stacked against them. DPF, AdBlue, EGR, catalytic converters, etc.

Audi’s price would have included a main dealer labour rate in the region of £200 an hour.

Search in LLL parts against your engine code for the actual DFP part.

So what’s the options? Would you consider fitting a used part if you could legitimately cross-check mileage? Prior to fitting I’d have it cleaned. Again, a garage may even be reluctant to go down that route,  given it comes with an increased risk, but it would reduce the bill.

Whatever you do, and hopefully you hang on to the car, start using Wynns AdBlue anti-crystal, and run premium diesel. Oil changes are a given too at 8k mikes tops.

Anyway, best of luck.

Edited February 7Feb 7 by spartacus 68

On 2/6/2026 at 12:03 PM, milfordnige said:

However I have started to notice sooting around the exhaust outlet.

I have watched enough of Jimmy, from O'Reilys Autos, on YouTube to know that soot on the tail pipes means one thing and one thing only. Your DPF is cracked. 

 

Thanks Das. Have you ever seen any explanation for why a fully maintained 50,000 mile car might develop a cracked DPF, bearing in mind the mileage has been a well balanced mixture of long and short trips?

It’s also just occurred to me that at no stage in the previous 4 years of dealer servicing including the August 2025 service has any mention been raised of sooting or of a DOF issue. The engine fault light issues have only been apparent from the time the Ad Blu tank developed a fault. Maybe a coincidence, but could the time it took the dealer to identify the Ad Blu fault and replace the tank might perhaps have contributed to the DPF issues - or is the Ad Blu system and the DPF unrelated…

I just wish I was more clued up! My dealer conversations have been less than helpful.

Most likely it would be due to excessive heat. Was you car ever subject to a static forced regeneration? Its literally the worse thing you can do to them, and should never be done.

1 hour ago, Das said:

Most likely it would be due to excessive heat. Was you car ever subject to a static forced regeneration? Its literally the worse thing you can do to them, and should never be done.

Hi you can't do a forced regen on post 19 cars they won't let it happen with the updated software you can only regenerate while driving same over all the VAG diesel range.

Steve.