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A6 Allroad Suspension Frozen With Cold!

Discussion in 'A6/S6/Allroad forum (C5 Chassis)' started by Mudplugger, Dec 2, 2010.

  1. Mudplugger
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    Mudplugger Member

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    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.
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  2. Mudplugger
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    Mudplugger Member

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    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)?
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  3. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator

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    Have you scanned it for faults?
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  4. murran
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    murran Active Member

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    compreesor and valve block is just infront of the spare wheel well behind the rear diff.

    if the cars dropping while parked you have a leak somewhere. most likely one of the front bags.

    if the car is sat ticking over on the same level height.... does the pump keep cutting in every few minutes? it shouldnt, if it is the system is trying to maintain is ride height/pressure due to a leak.

    worn pumps are noisy when cold and dont pump aswell when cold.

    you shouldnt really drive it with the level below 1, plus if there is a leak the car will feel unstable and bouncy and kinda like sitting on a bar stool with one leg shorter than the others......

    when you start up and the light is flashing press the "up" button, youll hear the pump working, if the car hasnt started lifting in like 20-30 seconds the pump will cut out and a fault will be stored. turn it off, start it back up and press the "up" button again. repeat this to get the pump temperature up (40 odd degrees), on about the third time of turning it off and on, the pump will be up to this temp, it will noticably quieten and the car will rise.

    you most likely have a leak and a pump thats on its way out.
    Last edited: Dec 3, 2010
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  5. Mudplugger
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    Mudplugger Member

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    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.
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  6. Mudplugger
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    Mudplugger Member

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    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?
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  7. murran
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    murran Active Member

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    the pump itself has a temperature sensor in it so the ecu can cut the pump out if it gets too hot in operation. sort of a thermal cut out.

    3 Faults Found:
    01400 - Suspension Level Control
    11-10 - Control Limit Not Reached - Intermittent
    usual fault that flags up when the pump cant get the car up to the the first level and cuts out insted of carrying on trying (ie, when the bottom light is flashing.)

    01772 - Signal from Level Control Pressure Sensor (G291)
    27-10 - Implausible Signal - Intermittent
    the system has a pressure sensor, might think its implausible if the pumps running but the system pressure isnt increasing. it will most likely think the sensors faulty?

    02538 - Function Restriction due to Overload
    35-10 - - - Intermittent
    hmmmm, not seen this one before. cant be refering to the cars overloading.... could be a temperature over load? (the thermal cut out i mentioned above?)

    tell me if im not helping lol?
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  8. murran
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    murran Active Member

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    the pump shouldnt "clatter" its a sign it not working very well. when theyre worn they seem to make this noise when cold, but the noise goes when the pump gets warm (thru its own operation). i suspect when its making the noise its not producing much pressure.

    from looking at the actual values on the diagnostics the temp goes up 1 or 2 degrees c every second or 2 that the pumps running.
    the 51 plate 2.7t allroad i looked at recently that had a similar noisy pump in the cold and poor operation to what your describing.

    imagine that the pump starts when you start the car, but after 30 seconds of running the pump cant increase the pressure to raise the car. now the allroad i looked at at work, once the pump temp seemed to get above 40degrees c it seemed to quieten and start working just fine. so imagine the pump starts off at air temp of 0 degreesc its not guna get to this 40degreesc in the 30 seconds it runs for before it cuts out and registers a fault.
    but if it starts off at an air temp of 10 degreesc it should get to this 40degrees in 30 seconds of running.

    monitor it and see what happens.......
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  9. The Slug
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    The Slug Active Member

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    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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  10. Mudplugger
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    Mudplugger Member

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    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.
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  11. Mudplugger
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    Mudplugger Member

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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!
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  12. Mudplugger
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    Mudplugger Member

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    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?
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  13. reggieroo
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    reggieroo Member

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    I was wondering myself if the freezing temps would play up the air suspension on our allroad but so far it has been great. We have had -19c & 10" of snow & I've been out driving in it for the last few days with no problems..........tell a lie, it hasn't been starting great in the morning, think the glow plugs are knackered but apart from that fine.
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  14. ms1083
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    ms1083 Member

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    Got a 2004 2.5TDI A6 allroad. 100,000 miles
    Had a few minor problems in the very cold period first thing in the morning (-10/-11oC)

    1st - rough once started, found that 5/6 original glow plugs had failed. Typically the one that is very fiddilly to remove (closest to radiator on passenger side of engine) was the one that did not need removing!! - they did nothing when connected to old car battery, after replacment perfect starting & smooth initial running. Do use good quality plugs, I used Bosch.

    2nd - Soon after starting had brake warning light, ABS & Suspension lights on, after turning off & restarting all fine but my fault code reader said intermittant signal from rear left speed sensor - have to guess it got frozen up as all seems fine now its warmed up a bit.

    3rd - After parking one side of car on pavement overnight once drove off it onto the flat the suspension control got confused, should have been on level 3 but jumped down to level 1 with warning light - again, fault code reader said faulty input from level sensor, think it must have frosted up. Also seems fine now.

    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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  15. murran
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    murran Active Member

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    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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  16. Mudplugger
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    Mudplugger Member

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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).
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  17. Mudplugger
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    Mudplugger Member

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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?
    #17
  18. reggieroo
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    reggieroo Member

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    I have used ours in deep snow (12") up a very steep hill into our village & it was great. It had new tyres on in September but only some cheap budget tyres & it didn't slip or spin once unless I gave it to much gas. I have found it great in the snow & have even tested it in the worst I could find. I reversed it into a tricky situation, when I reversed into a farmers gateway that was on a steeper incline than in looked because of the deep snow that had built up. I was almost looking at the sky & the misses said with a look of worry on her face "this will be a test" I said confidently "no problem" while I was really thinking **** we're going to get stuck but low & behold it pulled us out with a a bit of a spin it scrabbled up the slope to get us out, all of this in deep snow.
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  19. Mudplugger
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    Mudplugger Member

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    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...
    #19

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