MN-A8

With the recent cold weather in MN the air suspension has been acting up the last few days. I was driving home from the company holiday party and the green suspension light came on. A few moments later the yellow light came on and I noticed that the front end was getting a bit low so I pulled over. Keep in mind it was about 8 below at this point. A quick shut off and start up of the car cleared the lights and the front end raised up immediately. I was able to change from lift mode to hydraulic mode but it did take a bit longer to raise up to lift. I was able to make it home with no issues after that.

Fast forward to the next day and its 2 below outside... I am sitting in traffic and can hear the compressor running. It was fairly quiet in the car because the radio was off as well as the HVAC. The compressor ran and ran until the yellow light turned on. The compressor shut off at this time. I'm guessing it probably overheated but there was no reason for the compressor to be running; the accumulator had plenty of air. I was able to raise the car into lift mode a few times without the engine running (compressor doesn't run unless the engine is running).

The car has no leaks. Stayed put in lift mode overnight multiple times. I do the jack mode test every once and a while to keep an eye on things.

Level Control codes are:

G291 Pressure Sensor - Incorrect Signal

Upper Limited Exceeded (temp)


Hopefully someone can give me some info on what I am dealing with here. Is my compressor starting to give out? Relay getting stuck on even though the system doesn't need more air? Valve block valves frozen causing the pump to operate out of spec or unable to pump air? 2005 A8 128,1xx miles.

Thanks and Happy Holidays.

C-ked

Sounds like the suspension gremlins come out when it gets cold. Tough call

mishar

I vould start with the pressure sensor. I believe there is measuring block that can check the pressure.

MN-A8

This definitely seems to be true. It was slightly warmer for the past few days until this morning with a temp of about -9. The problem came back on the way into work. The car does sit in a garage, but unheated. Still warm enough to melt snow though.


According to that Air Suspension PDF the pressure sensor is in the valve block. I'm guessing that the whole valve block would need to be replaced to replace that sensor, if it is bad.

Thanks for the tip, i'll check the measuring blocks to see if I can find something.

jakematic

That is correct.
See this thread for part # - it's about a $450 item.

MN-A8

Wow, thanks for posting that. That is actually the exact same symptom that I am having.

I had lowering links and summer wheels/tires installed all summer so the car was never taken out of dynamic mode. When I switch over to my winter set I removed the lowering links and set the car to automatic mode. Ever since the switch to automatic I have had this problem. So maybe it is height dependent...

MN-A8

Hey Guys, I thought I should follow up and give an update. Maybe it will help someone else on this forum.

The problem with dash lights and inconsistent ride height was getting worse and worse. The car was not able to maintain ride height while in dynamic mode. My air compressor began to sound like a bunch of parts rattling around instead of an actual air compressor sound. I couldn't hear the relief valve on shut off either. I figured it was time for a new compressor with 130K miles on the stock one.

I bought a rebuild kit and installed the piston ring into the compressor. It was super easy. The hardest part was getting the compressor out of the car because the nuts holding the rubber and springs together were corroded from salt (Thanks MN). Once it was installed I immediately noticed a more familiar compressor sound and the car made it to lift mode in under 30 seconds. When the compressor shut off I got the lovely "PSSHHHH" sound so I know its moving air. I've been driving around in the 4 different modes for the last two months and have had no problems or dash lights.