j4g3d

Recently i've come across something really interesting.

I own a 4.2 TDI 4L Q7 and i came across a problem and the culprit turned out to be the regular engine bay fuel filter, which happened to be clogged with a black film all over it, £25 later and car runs great again (well almost!).

After digging around on this subject, i found that actually this car has 2 fuel filters. However, this is the strange part... NOBODY IN THE UK KNOWS WHAT OR WHERE THE OTHER ONE IS. Audi UK say there is no other fuel filter. WRONG there is and it sits in the fuel tank!. I believe the touareg and cayenne share the same parts. I desperately want to change this filter, and i CANNOT BELIEVE audi UK say the engine bay filter is the only filter and only serviceable filter... so so wrong.

These filters get dirty so easy, especially in cold weather. They need changing regularly to improve MPG/performance..etc.

So, i dug and dug and dug. And i came across this video:

I believe this is a petrol model? probably? seen as it appears to be in the U.S. Armed with this video and info in the comments section, i dug google, i came across these part numbers:

filter element:
7L0919679

complete housing inc filter:
229-025-011-001z

the problem i have now is; wherever i search online, it doesn't actually tell you if its for a diesel Q7. I can't help but thinking they're all for petrol/gas variants.

I went to the VDO website and downloaded their catalogue. Again absolutely no mention of a part for the diesel models.

Wonder if some search genius could help me out here?

lentiman

Have you considered the possibility that you are combining in your head the petrol and diesel fuel filters into one vehicle (which does not exist)? These are two separate filters for two separately fueled Q7's. What is your source of information that this second diesel filter exists? Not that I trust a dealer to actually know everything about their cars but it seems like you might be mistaken.

j4g3d

I am assuming it has one, what with all the video's and information i have found. The part numbers i found MAY be for both petrol and diesel models. Or it may not. But seen as diesel is dirtier than petrol, i'd be very much shocked if they fitted one of these filters in a petrol model but not a diesel.

j4g3d

(3) O ring says its for a diesel engine. So it exists.

2007 Audi Audi Q7 Europe market: Fuel, exhaust, cooling Fuel tank with attachments

j4g3d

Jeeze,can't you edit posts on this site??.

Look at number 8. It doesn't even give a part number. So they're not readily available from audi. They DO exist though. I am totally amazed that a paper filter that IS a serviceable part cannot be bought from main dealer.

Clues

I am pretty sure that your TDI only has one fuel filter. Unlike gas engines, Audi put TDI fuel filters that are accessible under the hood/bonnet since, as you stated, diesel has more contaminants and the filters would need replacing more often. On 5/31/2010 they changed TDI filters from canister (vertical) to inline (horizontal) filters.

The part number 7L0919679 and 229-025-011-001z are the same part (7L... is OEM VW/Audi part and 229... is aftermarket manufacturer part number). These are Fuel Tank Flanges with an integrated fuel filter. These are the ONLY fuel filters on gas engines and they are integrated into the gas tank. They can be changed by removing the rear seat bench, cutting away the carpet, disconnecting electrical connections and removing with a special T10202 wrench. This part is integral to the electrical fuel delivery system (it's not just a filter) and I am fairly sure it would be known to Audi technicians if it were indeed on the TDI models.

Since in you are in the UK and Audi has different variants there, I could be wrong in your case... I guess you could look under your rear seat and see if you see the Fuel Tank Flange?

https://www.audiworld.com/forums/att...lterchange.pdf

j4g3d

Just checked and it appears the carpet in my car continues throughout the car from front to back. Unlike the video of that touareg which seems to end under the seats. Mine does not do that. If there is access to the top of the fuel tank from inside the car, then i'd need to remove or cut part of the carpet out to get to it.

I think likely i will have this flange access, i very much doubt VAG group would make one chassis for petrol and another for diesel blanking off this part.

Clues

It would take you about 30 seconds to cut the carpet under the seat. If you really want to solve this mystery - then just cut it. Additionally, if your desire is to change this flange/filter (if you do indeed have it), you'll need to cut the carpet anyway...

j4g3d

I spoke to a guy selling these flange filters in the UK and he said they're for petrol models only. For diesel models it comes with 2 filters inside the fuel tank (rather than 1 which petrol models have). He said they're at the base of the fuel tanks and you can't just change the filters, you have to change the complete fuel supply unit inside inc pumps which is 260 GBP each. Ouch.

Still, it proves there are other filters on the fuel system, which audi told me there weren't.

I guess i will leave it for now, it isn't desperately needed. I was just tweaking with the fuel injection system on my car to increase performance further, but the car goes into limp mode when i tried the tweak at 3500rpm. I changed the engine bay fuel filter and the car goes into limp mode at 4150rpm. So to me, it seems there is something else clogging the fuel system up, which points to the filters in the tank. Hence my investigation into it.

Its a shame they made the diesel models so difficult and so expensive to change these compared to the petrol models.

Thanks

Gavin0478

It might be if you are tuning, by raising the fuel pressure or over fueling you may be hitting the max the pump can supply so throwing a fault code as it is leaning out.