A6 Allroad Suspension Frozen With Cold!

I took my Allroad out this morning in 6" of snow, -3C, and she behaved perfectly. The suspension sat at level 2, the ESP turned off when I pressed the switch etc. It was just like Audi had intended: safe and fun

I then parked up, with suspension on standard level 2, and left the car for the day.

When I got in this evening I realised almost immediately that the suspension was right down, even below level 1. The one solitary level light (for position 1) blinked constantly, and neither of the adjuster switches would 'lock on'. I couldn't turn the ESP off either.

I drove like this for 20-30 minutes, got out for 5-10 minutes, then restarted the car. For a few seconds, standing outside, I could hear a sort of "clattering" noise coming from near the back end. I've not noticed it before, but then I don't generally stand there looking to see if the car will rise up like an elderly Citroen DS either! It didn't rise so after a minute or so I got back in, and drove for another 20-30 minutes with the position 1 LED still flashing constantly, the adjuster switches unable to do anything, and the ESP still stubbornly refusing to deactivate.

I then stopped to buy diesel and, as I restarted the engine after that and drove off, resigned to more suspension-less banging and bouncing for the rest of my journey, so the car climbed back up to level 1 all by itself. The ESP deactivated when I pressed that button too. Then with a couple more presses of the 'up' button we went through level 2 to level 3. The car is now sat happily at level 4, in my drive.

I'm confident it's not a sensor fault because last time that happened the Xenon headlight self-levelling warning light came on, and stayed on for about a month until I fixed the sensor! I'm also confident it's not a punctured airbag because I have no warning light in the speedo to indicate the compressor working overtime, and if that was the cause it wouldn't have risen up after an hour and be sat tall now.

So I'm guessing it's something electro-pneumatic.

My first though had been that the compressor was frozen and couldn't pump up. But that wouldn't explain how the suspension came to be down in the first place...

While parked during the day I had unloaded a few bits from the car and occasionally when I have done this I have heard a 'hiss' from somewhere underneath, presumably as the car self-levels to compensate for the changing load or something.

So could this be what happened today? Except that this time the air dump valve (if there is one) got stuck open and couldn't close, possibly because of moisture in the sub-zero air icing it up? And being stuck open it simply drained the suspension of air, and rendered the compressor unable to refill it?

Has anybody experienced anything similar before?

Is this even how the suspension works, or have I surmised incorrectly? If I'm right, where are the dump valves, and what (if anything) can I do to stop them icing up again?

Finally, I have 200 mile round trip journey ahead of me tomorrow, so (increased risk of crashing aside...) is it bad for the car to drive with the suspension bottomed out like this if it 'collapses' or 'gets stuck down' again?


Any and all thoughts and advice greatly appreciated.

This morning the car was sat on level 4, precisely as I left it last night, and correctly dropped down to level 3 shortly after I started driving.

When I joined the motorway and accelerated up to 70mph the car, again correctly, dropped down to level 2. So far, so good.

During the next 90 miles I twice noticed that the level 2 height light was flashing, and the "up button" was flashing, suggesting that the car was trying to rise up to level 2. i.e. suggesting that it had somehow dropped below level 2. However, I had cruise control sat at 70mph and stuck to it, so there was no (good) reason for the car to consider dropping to level 1.

It's worth noting that when I left home there was 6" of snow and the temperature was -6C, there was a lot of spray on the motorway, and everything is frozen up firmly enough that the headlamp washers can't rise out of the front bumper.

So I'm still guessing at some sort of freezing fault with either the compressor, or the valve that dump the air out of the suspension.

Does anybody know where the suspension compressor air intake is located (under the car with the compressor, or somewhere remote so as to get warmer, drier air?) and where the dump valves are sat (again, underneath in the cold waiting to freeze, or somewhere remote and warm like the engine bay)?

And if they are all in the cold and wet, is there a "standard" mod to put them somewhere more sensible? Or should it all work OK anyway, and I have another problem (e.g. needing to service a compressor air filter or similar)?

Thanks Murran,

"just infront of the spare wheel well behind the rear diff" pretty much describes where I heard the "clattering" coming from.

The car's behaving fine now that the roads are a little clearer and it's a little warmer, which makes the problem harder to reproduce (not that I'm disappointed its gone away).

However, it seems that the car survives OK overnight on the height setting I left it in (as before), then cheerfully lowers itself down onto the bumpstops within 30-60 seconds of driving (when this fault is present). This suggests to me that I don't have a punctured bag or similar, thank goodness. It's worth noting that the first few hundred yards of my journey from home is a potholed track, which really exercises the suspension, and is one of the reasons I have an Allroad.

When you say "40 odd degrees": are you talking farenheit or celcius? I struggle to imagine the pump reaching 40 celcius in the current climate, with air temperature hovering around zero (and that only now it's started warming up again).

If it goes wrong again I'll do exactly as you advise, many thanks for the tip. You sound as though you've been there yourself!

I'm hoping to get out there later, plug in my VCDS, and scan it to see what the electronics can tell me. That's if I can figure out how to get this detailed with VCDS anyway, as I've not had it long

Thanks again.

Having now scanned with VCDS, here's what I found...

-------------------------------------------------------------------------------
Address 34: Level Control Labels: 4Z7-907-553.lbl
Part No: 4Z7 907 553 F
Component: - 2C1A1 D060
Coding: 25500
Shop #: WSC 00539
VCID: 4895ABBB42C1

3 Faults Found:
01400 - Suspension Level Control
11-10 - Control Limit Not Reached - Intermittent
01772 - Signal from Level Control Pressure Sensor (G291)
27-10 - Implausible Signal - Intermittent
02538 - Function Restriction due to Overload
35-10 - - - Intermittent

-------------------------------------------------------------------------------

I've cleared these faults too, so as to know for sure which (if any) recur.

My crude guess is that cold/wet perhaps got in somewhere it shouldn't have and temporarily messed up a sensor or two?

Hi Murran,

What you're saying makes a lot of sense, thank you.

I've also been looking this up on other forums e.g.

Not Another Air Suspension Question.... - Page 2 - AudiWorld Forums - which advises lubricating the compressor to provide a better seal and improve pressure when cold

and

quattroworld.com Forums: Advice needed: Is this a leaking air spring? - where the problem seems to stem from an air leak

finally

Audi Allroad - AudiWorld Forums - which suggests that the G291 sensor itself may be faulty, and explains where to find it

Having read and considered them all, and taken on board your comments and advice too, my plan is as follows:

1. Wait until the weather improves and or my heavy cold goes away
2. Get in/under the car and find the compressor and attached G291 sensor
3. Lube the compressor with air tool oil (nothing else)
4. Remove and clean the G291 sensor, squirt with silicone after refitting

If I do then transpire to need a new compressor, this appears to be the palce to get it from: New WABCO Air Suspension Compressor/Dryer Assembly for 2000-2006 (C5) allroad quattro

Thanks for all your help and advice, I'll post back here afterwards (may be a few weeks) to share the knowledge for everybody's ongoing benefit.

The Slug said:

seems strange....when u think that these cars are tested in countries that go below temps we've been getting recently....man every Allroad owner in sweden would be screwed lol

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Audi tends to test their cars when new, mine is 7 years and 130,000 miles past that status, so I'm not sure how relevant your comment it. It's obvious enough that the car was designed to work in snowy conditions, that's partially why I bought it; what I'm trying to figure out is why it now doesn't work properly!

So I did (almost) as planned: I found the compressor air intake (in the spare wheel well), pulled it out, disconnected the air intake, and poured a quantity of air-tool oil down it.

I then cycled the car up and down a few times to work all this oil through the pump. The pump was very quiet on sucking, in fact I couldn't really hear it working at all, yet quite vociferous on blowing when a quantity of oil was also blasted back out. From what I've read elsewhere this isn't a good sign as it suggests that my pump is weak.

My main concern however is that while I was busily going up and down through the suspension range, specifically when trying to raise from L1 to L2, the car suddenly started to emit a loud "hiss" from the front left corner and the suspension sagged right down on that corner, even below the L1 setting. The rest of the car stayed correct, on L2.

My first thought here was that I must have an air leak somewhere, maybe even a punctured air-spring, yet after eventually raising up to L2 the car then sat there happily, even with the engine turned off overnight. So maybe I don't have an air-leak?

Can anybody comment on this?

The oil is starting to work incidentally, and the car raised from L2 to L3 when I started driving in a temperature of -12C this morning, correctly dropped down to L2 for the next 100 motorway miles, then happily raised back to L3 in about 20 secs after I pulled off the motorway. So I'll also recommend trying an application of air tool oil to help breathe some life back into a tired compressor.

The car is currently parked in L3, and has been for 7 hours, no problem.

But as to the hissing noise from the front left corner, and resultant lowering of just that corner, I have no idea. Does anyone?

ms1083 said:

found car very good on slippery ice but bit dissapointed in deep snow on a hill, first winter I have owned the car. It has budget tyres on the front and pirelli allroad on the rear - all only about 3mm I was hoping to replace all of them with new pirelli allroads in a month or so just before I would have expected snow but it came early!! Have bought 16mm snow chains for the rear tyres so I don't have to dig myself out for an hour and a half next time. As a large animal vet quite likely to have to go places which can be quite slippery/snowy.

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I see this is your first post, so welcome to the forum.

Good though the Quattro TCS is I think you're asking a lot of it to get you up a hill covered in deep snow with only 3mm of tread left, and 50% budget tyres at that.

Don't overdo the snow chains on the rear or you'll otherwise wind up destroying those Allroads before you get to the time to replace them.

I am thinking of buying myself snow-chains now too, just in case I have to take to the back roads to avoid a blocked motorway (like in last year's snow).

murran said:

btw, at the beginning of the week. this allroad i was refering to ^^^^ it came in at work. i fitted a brand new pump from tps......
now from the pump being stone cold, it works spot on! its quiet as a mouse and goes up suspension settings in 5 seconds flat!

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Well, I've certainly got to do something with mine: yesterday evening it jacked itself up to L4 at 70mph on a motorway and has since refused to go back down again. The ride's rock-hard, and I'm not convinced it's good for the car either. I'll be posting full details later, after I've had a chance to plug in VCDS and get some idea as to what it thinks is wrong.

Chances are it's electronics/pump-related though, so do you have contact details for TPS, please?

Mudplugger said:

The oil is starting to work incidentally, and the car raised from L2 to L3 when I started driving in a temperature of -12C this morning, correctly dropped down to L2 for the next 100 motorway miles, then happily raised back to L3 in about 20 secs after I pulled off the motorway. So I'll also recommend trying an application of air tool oil to help breathe some life back into a tired compressor.

The car is currently parked in L3, and has been for 7 hours, no problem.

Click to expand...

In light of the fact that my car is now stuck on suspension Level 4, having raised itself there while I was driving at 70mph on a motorway, and refuses to go down again, as described in this post...

http://www.audi-sport.net/vb/a6-s6-...9740-allroad-suspension-stuck-level-4-l4.html

...I'm withdrawing my recommendation of pouring tool-oil into the compressor until I know for sure that it didn't contribute to the problem!

Meanwhile, if anybody has any recommendations as to how I can fix the problem as my car is now effectively undriveable, I'd be very pleased to hear them, please...