A6 C6 rear suspension dropping

[PaulF2.5TDi]

I've had a look around here and elsewhere and it appears that (unlike the C5) this is not a common problem as I only found a couple of faults that were not the same as my issue.

Just recently, if the car is left for a couple of days, the passenger rear side drops to the stops from the 'Automatic' setting.
On starting the car, the green suspension light remains on for a short while until the car has risen a little and puts it out.
I have not tried any other setting yet (that's the next test when the car is going to be left idle a couple of days)

I have scanned it with VCDS - no fault codes, although as I think as soon as the ignition is switched on the pump starts.

I had a battery that was just starting to fail, which I have now replaced and coded a couple of days ago.
The only way I knew about the battery was if left for a few cold days the car would start normally, but the battery protection system had cut in.

I would have thought that if the level sensor was u/s, it would give a code or amber caution light.
Equally if the spring or pipes leaked causing it to drop, the car would not be in the position selected, so I would expect a code or fault light.

I have had a look with VCDS at what is going on but the labels are a bit lacking so I'm unsure of what many of the measurements are.
It appears that one of the blocks is the ride height as on reading is lower than the others and it seems to come up with the engine on.

I'm going to try and leave it on different settings and see if that helps, then trace the pipework with a fairy liquid filled brush looking for leaks.

Any pointers on where to look or what VCDS reading are worth looking into?

[Duggy72]

Try sending a message to bag piping Andy from the c5 section. He is an expert on these matters. Sorry I can't be of more help.

[motionpotion]

I have very similar issues with my 2006 A6 Allroad. Initially mine started out as dropping on the right hand side rear (drivers side rear) after a few days parked and only in automatic mode but it has now started to drop within an hour of stopping the car and on both passenger and drivers side on all of the height settings (automatic, dynamic, comfort, allroad) settings.

I also have no fault codes. But I do have a battery problem which I think is related to the compressor trying to run all the time to keep the air suspension inflated while stopped.

I would also like to know how to fix this - hopefully without having to buy new air suspension.

[PaulF2.5TDi]

Thanks Duggie - I probably will at some point as I'm not a million miles from him.

I saw your issue Motionpotion - the battery did not fix mine although it really turns over fast now!

I'll try and look over the next few weekends, but I suspect a valve in the solenoid block not sealing properly.
If this is the case I expect it will be a bugger to find.

If I find no leaks, I'll try some light oil through the solenoids - the environment my cars live in is not nice!

Do you have the problem at other settings?

[motionpotion]

@PaulF2.5TDi I swapped in new battery tonight and it's turning over faster but didn't fix anything with suspension.

Mine drops on back right drivers side at Dynamic, Automatic and Comfort settings. It does not drop at Allroad until about 2 days parked up and then it drops evenly on all corners.
I have not tried parking it up in Lift setting.

[PaulF2.5TDi]

An update on this - for what it's worth!

I haven't fixed it yet - but there are more clues.

The car seems to drop overnight - not slowly over time.
It can go a week without dropping, or (last week) drop whilst at work (dynamic).
It is only one corner that goes down.
There are no fault codes in VCDS.
The flashing green and yellow suspension lights may or may not come on. (I suspect if the yellow light is not on it hasn't dropped enough to trigger it)
The lights do not always go out once the car is back up - switching ignition off and starting again clears them.
It doesn't seem to matter what ride setting its on - although 'locking' it in Jack mode seems to stop it. (Although the drop in Dynamic may have been in jack mode too)
It appears to happen more often when it is cold (temps around freezing)
The suspension module had the wrong code when I bought the car last April (no tow-bar bit set) so I wonder if it has been changed already for this problem over the last winter by a previous owner.


This does not seem like a leak - more an intermittent module or sensor issue, but would this happen with the cars ignition off when parked?

[MarkTM]

For those without air suspension that's what's being talked about in this thread