D3 4.2TDI DPF Pressure Sensor
 

Apologies for my first post being a request for help but I have been a lurker for a while and an A8 parts customer :)

I have a 2005 A8 4.2 TDI, circa 125K miles on the clock and it has just started showing an amber engine warning light, I have checked with VCDS and the following error is showing. Clear the code, the light goes out for a day or so and then returns.

Google suggests that I need to replace G450 or possibly G451 sensor? Has anyone come across this before or can you give me any tips? Is the part something that is best from a dealer or elsewhere and where will I find the sensor on an 8?

Thanks in advance +++

Paul

It could be the filter is choked, there are products available to clean them out

I think the DPF is okay in itself, I think the sensor is the problem given the "Implausible Signal". I have found the code for other VAG engines and the fix seems to be to change the sensor, just not sure where it is on A8 :hammer:

I found the number G524 for bank 2 sensor and G505 for bank 1 sensor

See attachments for location of connections and sensors

Hope this helps

I agree with your thoughts, I'm sure the DPF will be OK it is just the Pressure Difference sensor that is unable to calculate the difference in pressure before and after the DPF therefore it cant decide how clogged or not-clogged it is.

Note that while it is broken it wont try and do any re-generation of the DPF so I would suggest a replacement sooner rather than later. I had to change the one on our Crafter for the same reason, easy job, and afterwards I used VAS to force a regeneration although I dont think that is vital - once fitted it should sort itself out.

We can get hold of one from TPS if you need, just let us know via email or a call on Monday morning.

If it is expensive, I would put the money towards having the filters taken out of their boxes and trashed and then ECU reflashed sans DPF.

I had mine taken out at 175,000miles due to blockage and it is much better without. You have two and it costs about £2400 to replace them!

What a great forum!
 

Ah, okay so looks like I need a G524 then :) Shame it looks a bit of a pain to get too "on gearbox rear" but I will give it a go!

I was working form what I could see in this doc http://www.volkspage.net/technik/ssp/ssp/SSP_365.pdf but the info posted above looks more specific to my car so many thanks 47p2 +++

David, I will send you an email shortly and would be very appreciative if you could source the part for me +++ Will try and get it fitted ASAP and post back how I get on.

Thanks to all :cheers:

Bank 2 looks to be sensor G505, double check numbers before ordering!!!

Also see attachment for sensor G450 which is the exhaust pressure sensor

Well guys, having been under the car and re-acquainted myself with ELSA I am now wondering who in their right mind in Germany decided the est place to mount the sensor was on the TOP of the gearbox!?

£60 for a part, I suspect it will be a lot more in labour as lowering the subframe isn't something I want to try on the drive with a trolley jack and stands :mad:

Will call around tomorrow and hope that the actual labour involved isn't as bad as it sounds! Thanks for the help thus far +++

I am glad I was sat down when I called my local dealer for a quote, 7.5-8 hours @£145 per hour +VAT, so over £1,300 in labour, oh and £47.86 for the actual part :ROFL:

Actually it was worse than that, their tech suggested it was actually the lambda sensor as "your car doesn't have a DPF sir"! When I explained that it clearly did have TWO of them and maybe he should check they spoke to the master tech who advised that apparently they need to "remove the gearbox", which is weird because that's not what ELSA says but what do I know!? :Confused: In any case, not very confidence inspiring!

Now awaiting a call back from a couple of indi's who hopefully will know their arse from their elbow! :D

Typical of todays 'fitters'

All the more reason to have the blasted thing deleted.
We are Euro 5 emission-regime R&D guinea pigs on the road and at our expense.

It is quite unbelievable that you are being asked for £145/hr for a technician who doesnt appear able find his ar$e with both hands! I mean, £1160 day is getting towards the cost of a lawyer or accountant from PWC (not that they would be any good for this - or much else - but you know what I mean!):rolleyes:

Don't knock a decent dayrate :p

The Tech is getting about 20% of that if he's lucky, the rst goes to the posh showroom and all the managers etc.

Well I have a second quote from another local dealer, 4.8 hours at £105+VAT and they seemed to talk some sense recommending changing BOTH sensors as the main cost is labour - £700. Better but still seems a lot!

I have called a couple of local indi's but they don't seem keen to take it on, I am awaiting calls back but I guess I won't hold my breath, will chase tomorrow and if I get nowhere will book it in with the dealer for an easy life.

I want to keep the DPFs, having owned many diesels I actually like the lack of black crud at the smelly end of the car, much more civilised especially when you boot it! I know it costs me a bit of extra fuel but I personally think it is worth it to keep the original spec. To remove the DPFs I guess I'd need a remap which is likely to have insurance implications would (in my mind at least) give me some concerns about reliability..... perhaps it's just me!?!?

So I now have prices from three dealers, in turn they quoted for 7.5-8, 4.8 and 2.5 hours to do the same job of replacing both sensors!?!? All main dealers, all quoting for exactly the same work and a price range of £410 to over £1400. I have no idea how they plucked those figures from out of the air!?!? :rolleyes:

I spoke with a local VAG indy who are going to replace both for ~£200, booked in for a week on Monday as that was as soon as they have a free ramp :)

Amazingly the dealers could all fit it in "tomorrow", I wonder how busy they aren't or if they ever wonder why!?!? :ROFL:

lol thats outrageous - almost worth a letter the Audi H/Office at Milton Keynes to highlight the crazy variations and the un-comptetitiveness of their workshops on this occasion, you never know what they might say or offer if you are "disappointed enough"! +++

At 125k your DPF's don't have much life left in them. So whilst you might pay £800 to replace these sensors, unfortunately you might do this and then your DPF's are too far along to work properly.

Most DPF's give up around your mileage. Granted your V setup means less flows throught them but still.... I would gut and remove.

I've just had the DPF removed. She's sweet as a nut and at a fraction of the cost. Wouldn't hesitate to do it again on another A8 as I now know I've never got to worry about it again. +++

I actually did the filter removal myself and just had the ECU reflashed. Easy peezy

Bex

Just a quick outcome and hopefully my last post on this subject, after a lot of research into the potential issues and longevity with the DPFs on my car I decided to keep them! There doesn't seem to be any specific cases of failure on this engine so long as the car is services properly, but if there is then I will probably get them cleaned or replaced rather than removed because of the potential insurance issues of exhaust "modification" and required re-map.

I had both sensors replaced by a local independent VAG specialist and all seems to be back to normal. Total cost £290 in the end as I needed to get some exhaust clamps replaced too.

If anyone is needing work in the Manchester area I can highly recommend VAGtechnik, they did a good job for a much more reasonable cost than any other dealer/garage I tried and didn't just make it up as they go along like the main dealers seemed to be doing! :ROFL:

That's a bit better than one and a half grand, but I bet you didn't get a tin of Audi travel sweets and a wash and vacuum sir!+++

No sweets or half done valet, but they did top up my screen wash "because the light was on". A massive +++ for VAG Technik :D

Audi could learn a thing or two about customer service from some of their ex-mechanics who set up as independent specialists!!!! :ROFL:

£290 is a fair price :)