2009 Audi A4 B8 3.0 TDI Quattro - a list of problems...
2009 Audi A4 B8 3.0 TDI Quattro - a list of problems...
Author
Discussion

Ray Singh

Original Poster:

3,066 posts

251 months

Thursday 13th November 2025
quotequote all
Thanks for reading.

I bought my B8 shape A4 3.0 tdi estate from a probate sale for £1k and what a car. Its powerful and large enough to carry my family anywhere, fast and comfortably. It can be used for the tip run too and saves my 911 and Alpina from these dull duties. Its a well spec'd car with leather, 6spd gearbox, 18 inch wheels etc. My kids call it the dog car, but to me, it is a god send and a truly practical vehicle to munch miles in frugal style.



However, It came with some problems.

1. Radio all worked fine and then today, no volume at all. Not from the radio or the CD changer. The small knob on the centre console mutes, but nothing else. I tried a MMI reset and even disconnected the battery for a few minutes today - nothing.....
2. The passenger side electric seat heats, but the electric seat movement does nothing. Is this related to the water leak?
3. The car has a panoramic sunroof, which opens, closes and tilts as it should. However, the blind is stuck in the closed position. I tried the 'adaptation' but this did not work.
4. Parking sensors feature on the rear bumper of car, but there is no park assist featured in the MMI. Is this normal?

The car also leaks water into the car in the passenger footwell. I have checked the sunroof drains and all seem clear. The water seems to come in from under the glovebox and manifests itself in drips on the plastic sill and a large puddle in my passengers feet.

Any help appreciated. Is there a 'go to' place for correcting these sorts of issues on Audi in the UK?

A youtube video promoted a place called Satnavsystems in Surbiton - Does anyone have any experience of these guys?




stogbandard

419 posts

71 months

Thursday 13th November 2025
quotequote all
Water in the footwell:

Blocked plenum drains and/or

Bad pollen filter housing seal.

J886ATV

146 posts

111 months

Friday 14th November 2025
quotequote all
Experiencing similar problems of a sieve like B8

Stereo issues - check the compartment on the left hand rear of the boot where the Amp / MMI system is - mine was soaking. My MMI has the symptoms shown in https://boserepairexperts.co.uk/ where it just doesn't start up - suggesting the AMP has been water damaged.

Front leaks is often the drains in the front scuttle - they don't seem to clear very well and you end up with water in the front footwell.

Who'd have thought that cutting a great big hole in the roof would cause issues 15 or so years down the line.........

catso

15,654 posts

288 months

Friday 14th November 2025
quotequote all
J886ATV said:
Front leaks is often the drains in the front scuttle
Sounds a likely cause.

Not an Audi but my Son had a Clio that would regularly block the drains. First symptom was usually a misfire as the blocked drain caused water to overflow onto the RH end of the engine and would fill up the no. 4 sparkplug hole around the coilpack and cause a misfire.

A simple 'rodding' with a stainless welding rod and picking the leaves out would cure it.

Dr G

15,744 posts

263 months

Friday 14th November 2025
quotequote all
Sat nav systems are good for things like control module repairs, and yes, your lack of noise will be a wet/failed amp in the NSR quarter.

Adrian E

3,333 posts

197 months

Friday 14th November 2025
quotequote all
Pull the plastic cover off from under the bonnet at the scuttle (the one with the removeable cover to access the +ve battery terminal connection). If the drains are blocked there, you'll see a pond of water and detritus. I used to take mine out annually to clean all the leaves and crap out and make sure the drains were clear.

gregpot2000

290 posts

165 months

Monday 17th November 2025
quotequote all
In that era for the parking sensors, its working normally.

They are only audible when rear only, you need front and back sensors to get the display - PDC plus I think the option was

Ray Singh

Original Poster:

3,066 posts

251 months

Tuesday 18th November 2025
quotequote all
Thanks for the replies and help.

Update. I went to see SatNavSystems in Surbiton on Monday. A decent bunch of people who know what they are doing.
Within the hour, they diagnosed a faulty amplifier in the boot. They showed me the board and it was obvious that there was water damage. They suspect that it was moisture in the car, rather than direct water ingress.

The important bit - To fix £770+vat for a new amplifier!!!! I only paid £1000 for the car....

I will see if i can locate a part number for the B&O amplifier and buy from Ebay. Stand by!!!!

J886ATV

146 posts

111 months

Friday 28th November 2025
quotequote all
Ray Singh said:
Thanks for the replies and help.

Update. I went to see SatNavSystems in Surbiton on Monday. A decent bunch of people who know what they are doing.
Within the hour, they diagnosed a faulty amplifier in the boot. They showed me the board and it was obvious that there was water damage. They suspect that it was moisture in the car, rather than direct water ingress.

The important bit - To fix £770+vat for a new amplifier!!!! I only paid £1000 for the car....

I will see if i can locate a part number for the B&O amplifier and buy from Ebay. Stand by!!!!
Tis always cheaper up north! https://boserepairexperts.co.uk/audi-a4-a5-s5-bang... are on my bookmarks ready for when I send mine away

Ray Singh

Original Poster:

3,066 posts

251 months

Monday 1st December 2025
quotequote all
Thanks J886ATV.

These guys have a comprehensive looking website and look good. I made an enquiry and was asked to provide a part number of my amplifier.
I took it out of the car today and have a sneaky look at the pcb.

Defo signs of water ingress.....






Part number sent to 'tut guys up norf. I will keep you all updated.

Ray Singh

Original Poster:

3,066 posts

251 months

Wednesday 10th December 2025
quotequote all
Ok, so water damaged unit sent to the Bose repair Experts. They are confident that they can rescue this.

Whilst the unit is away, i need to find where the water ingress in the car is coming from. I have had the usual water in the footwell story and am glad that the car came with rubber floor mats!



I took part of the headlining down and was shocked to see mould and water staining on the back of the headliner itself. I bought some CT-1 silicone and adhesive as i thought that the issue was the water drain pipes. When i pour water into the channels on the sunroof, i can see that the seals of the little white part was perished where it joins the pipe. I sealed this and also added a bead of sealant to the inside of the fitting and put back on. I've only been able to get to the front two drains at this point









I tried with water again and noted that the leak is actually coming from the frame itself. A lot of water!!! Checking the internet, this is a common issue and a new frame is over £1000!!


It now seems that I will have to take the headliner down all together and then the sunroof cassette and investigate and reseal, before fitting it back to the car again. Who designs this rubbish? It might give me something to do over the Xmas vacation, i cant bear watching Only Fools and Horses again..... I might be able to investigate the sunroof blind operation whilst I am in there......

Edit - is there a liquid waterproofer that I can paint onto this to make it water tight and avoid removing the lot from the car?
Edit Edit - I also contacted Webasto who have an office in Doncaster to see if they can help with technical diagrams and the bonding agent used.

Edited by Ray Singh on Wednesday 10th December 20:48


Edited by Ray Singh on Thursday 11th December 11:42

J886ATV

146 posts

111 months

Thursday
quotequote all
You get your amp back from https://boserepairexperts.co.uk/ ?

Mine came back all working - really pleased with the service

Water traced to holes where a previous owner has knocked the rear quarter and the bumper brackets were held on with self tapping screws through the body (and subsequently some had rusted away leaving easy water access). Now repaired / sealed and a new bracket fabricated / welded to hold the bumper in place.

Ray Singh

Original Poster:

3,066 posts

251 months

Apologies for the slow reply. I had a frantic Xmas and New Year with family bereavement.

The Amplifier came back from Bose repair experts fully repaired and with a clean bill of health. It also has a nice cover that will keep water out of it.
Total cost around £260 a massive saving on the £700+vat i was quoted. Thanks again for the recommendation!

Before fitting it in the car, I wanted to make sure that all water ingress had been stopped, otherwise installing the refurbished unit in a wet car would just result in the amp blowing again. I found this useful although for VW Golf. https://static.nhtsa.gov/odi/tsbs/2017/MC-10128041... Its a technical bulletin for a VW Golf in the US and associated repair kit.
I couldn't see any cracks in the cassette from inspection, but pouring water in the sunroof channels - it poured out of the drain tubes, around the white connector and also along the cassette seams. I used Tiger seal to bond these all and tested with water, 24 hours after each application of the seal. After 4-5 visits, i was confident that it has sealed. My advice, pour water - see where leaking, mark, wait for it to dry and tiger seal within an inch of its life!! Goto step 1.




I have found time to put half the interior back together and managed to loose a clip for the sun visor and destroy the grab handles. They are no longer self retracting.... Argh....





Importantly, the amp is back in and the MMI is alive once again. I can listen to FM radio once again.

Next task - why doesn't the sunroof shade work?