A6 Allroad estate, front end dropping

[Brian Howard]

I have a 2011 A6 Allroad estate and when left parked up, after a two or three days the front end drops. When I start it up the front end lifts up without me changing anything. When it does this the green (car icon, with 'down arrow') illuminates until it has reached height. Then it goes off. When I test the raising and lowering it behaves properly.

I bought this car two months ago, and it's my 2nd Allroad estate. The previous owner spent over £2770 on the air suspension in December 2023 with a non Audi garage and had the compressor, air suspension valve and air suspension spring replaced. 

The F/N/S drops more than the F/O/S and settles about 2cm lower.

When it's parked up, and I open any of the doors there is a quick 'hiss'  from the F/O/S, behind the wheel area. A bit like the air brakes on a lorry. It will do this if I continue to open more doors. It will even 'hiss' when it's parked up and nobody is touching it!

Yesterday, the suspension had dropped as I hadn't used the car for about  3 days and after I had vacuumed the inside and had all the doors open, I noticed that the front suspension had lifted itself up! I had not switched the ignition on or anything. I did not hear the compressor running, but then I did have the vacuum going and it's quite noisy.

The car is quite old and has 168,000 but it is tidy and runs very well. 

I would appreciate any opinion on what the fault might be so that I can minimise the cost of fixing it. 

Thank you.

[Steve Q]

I'd definitely say a leaking suspension airbag. 

[Brian Howard]

Hi Steve. Thanks for responding.

Is there a suspension airbag for each corner then? If there is, and I guess that would make sense, then do you have any idea why the 'hissing' noise is coming from the F/O/S when it's the F/N/S that's dropping?

Is a replacement a big job? 

I forgot to mention that I have had a diagnostic check done by a former VAG technician and no fault codes came up? That's why I'm trying this forum because I can't afford an Audi dealerships charges just to find a fault. 

 

Thank you

[spartacus 68]

Consider getting VCDS yourself. It’s pretty invaluable with these types of jobs for fault finding. Check out Gendan site. You can get 3 VIN for around £220 and unlimited upgrades via Rosstech. You’ll also need an old laptop to run it on.

Back to issue, if previous owner paid nearly £3k, and that included compressor in 2023, then that kind of rules out the compressor in my book. Each wheel has its own suspension unit, plus air line and union seal to the unit. You could do worse than spray soapy water on the area you suspect and sit it out and look for bubbles.

VCDS may identify, but it’s useful to reset, clear faults, etc. It needs to be under load, so removing the wheel to observe may not repeat the fault.

[Brian Howard]

Hi Spartacus 68

Thanks very much for your response. I've had a look at a VCDS unit on that website. Not sure I can afford that kind of thing when I wouldn't really know how to use it to justify the cost.

Thanks for explaining about the suspension unit and parts. Useful to know. It does sound like this would be the culprit. I just can't figure out why there's a 'hiss' coming from the opposite front corner though. It would make more sense for the noise to come from the F/N/S as that's the corner that sinks. 

Appreciate your time. 

[Steve Q]

15 hours ago, Brian Howard said:

Hi Steve. Thanks for responding.

Is there a suspension airbag for each corner then? If there is, and I guess that would make sense, then do you have any idea why the 'hissing' noise is coming from the F/O/S when it's the F/N/S that's dropping?

Is a replacement a big job? 

I forgot to mention that I have had a diagnostic check done by a former VAG technician and no fault codes came up? That's why I'm trying this forum because I can't afford an Audi dealerships charges just to find a fault. 

 

Thank you

Yep one in each corner. 

[Brian Howard]

Thanks for clarifying that Steve. I'm learning!

[spartacus 68]

Air suspension can be complicated. The old C5 A6 Allroad was plagued with issues and it's expensive to put right. The reason I suggested VCDS, is it takes a certain amount of the guesswork out of fault finding and can help with calibration if and when it's fixed. You have headlight levelling sensors on the car front and rear, but suspect they'll be okay if car is resetting on start-up. That said, if you're not spanner handy, then the car will need to go to a trusted independent garage. Personally I'd avoid the main dealer at all costs or you're literally talking thousands given it's 2011 build. They tend to throw parts at a situation to resolve.

If you bought the car privately - you'll have to absorb the cost to put right. If you bought it retail through a second hand dealer then you are protected via Consumer Rights Act 2015, but only for first 30 days. If the fault has arisen outside this period, then speak to them. Normally car warranties, say 3 months aren't worth the paper they are written on and are often under-written by third parties with more small-print than you can shake a stick at.

[Brian Howard]

Hi Spartacus

Many thanks for all the detail. Very much appreciated.

I bought the car privately knowing there was a fault so it's a case of caveat emptor. I am still very happy with it as overall it's in very good nick. I'm just trying to assess if I should just live with the fault or, find out what the fault is then consider paying for a fix.

I'm attaching the invoice I received with the car. What I can't figure out is that under labour, it says 'fit N/S/F suspension strut' Quantity of 2, but no cost? (This is the corner that drops the most).

Question. Is 'suspension strut' the same as air suspension spring? Because the latter is listed as parts charged for, no listing for strut. 

Is either of these another name for air suspension bag?

If you've had enough of this, feel free to say so or just ignore me. I realise I may be imposing on your time.

Thanks

A6 Allroad suspension.odt

[spartacus 68]

That's not the invoice. Got any part numbers? Genuine Audi will be around £2k. Will be dependant on engine, chassis, etc. I don't recognise half the brands on Autodoc, but Arnott, £600+ and Bilstein £800+. Classed as air suspension strut. They are not servicible item as in repair, if it leaks - replace. The air pipe to the air suspension strut would be worth a look, just to make sure it's not leaking there. Before you do anything - double check the part number. Suspension even on standard springs is a complicated. The springs are rated for the car and there are multiple options. Similarly with air suspension, there are the related components.

I know this isn't for your car (C6 S6 airbag), but pictures are decent and it lets you see what it's like. https://www.ebay.co.uk/itm/274680663622

LLL parts showing more detail: https://www.lllparts.co.uk/product/4F0616039AB

[Steve Q]

21 hours ago, Steve Q said:

Yep one in each corner. 

No probs at all. The bags replace the conventional suspension set up of springs. 

[spartacus 68]

8 hours ago, Brian Howard said:

Hi Spartacus.

Here's the full invoice, there are no part numbers but I have written to the garage to ask for more detail.

Thanks for the links to the parts, I have had a look. I was a mechanic on VW/Audi back in the 70's but that was way before air suspension came in. I can find my way around cars a little but I don't have the tools or knowledge to be poking around these modern lumps of tech. It seems you need a degree in computers, not a set of spanners.

I will have a look for this air pipe, on both sides.

I parked it up yesterday in Allroad mode. 24hrs later the F/N/S had dropped 3cm, the F/O/S 1.5cm. Any more suggestions?

 

I'd take that invoice down if it were me (you can ask admins), it has personal information on it of the last owner. If it was genuine Audi parts, they carry a 2 year warranty. All I can see on there was the garage took it to Audi, probably to reconfigure the air settings. It can't have just been to scan it. VCDS can reset settings. There's probably not much you can do until you determine where the leak is. To be honest fitting the air suspension is not overly complicated, however any suspension work has underlying problems with siezed bolts, plus access to a lift would be useful. I bought air tools a couple of years ago because I've had Audis for years, and broken springs are part and parcel of running them.

If it were me, wash the car at the weekend. Snowfoam under the arches and remove the wheels and use a light brush to agitate the air strut, then jetwash. The area needs to be clean to see any leak. Get a light detergent and spray both front corners with wheels off to see if you can observe anything. Also check the valve body. Same procedure, but don't soak anything. Its just the area where the air lines from the valve come from.

[Brian Howard]

Thanks for that Spartacus. I will try and remove the invoice. I understand what you're saying. The previous owners no longer at that address but I will remove it anyway. 

I appreciate your suggestions and I will give it all a go. Not this weekend though as I have to run some people around. I'm retired so I can do it anytime. It'll be interesting to see what's under there and I can compare it all with the links you sent. 

I'm grateful for your time.

Brian

[Audi Owners Club.]

The invoice has now been removed as requested by the OP