Leondrew

Thank you.
The up and down button only work when the car is in stationary or not above certain speed limit. I am just confusing why the car can stay at certain level for days or months if there is any air leak. I didn't see obvious oil leak but a tiny drop may possibly ruin the sender's signal. The car is now at 100,000 mileage, which is a good number that will need a replacement for the air suspension unit according to what I have found online.

Romario

Control module not necessary to replace after 100000 mileage. You are not understand how it is working. I can explain in km/h only.
Second level is normal position. It is design.
You can up suspension level to 3rd or 4th level without moving or...
- 4th level limit till 30 km/h, after reach of speed limit suspension lowering to previous level;
- 3rd level limit till 80 km/h, same situation;
- 2nd (normal) level limit will keep till 135 km/h,
- 1st level will keep down during full stoppage.
After stopage suspension will restore 2nd level or you can stop movement manualy and keep level in 1st position.
Please read SSP243 file and compare functionality of your system. If your car doesn't drop down every morning, not necessary to finding problem itself. Do not disturb the mechanism to work.

Leondrew

Thanks. The main problem is that the car will not stay at level 1 but keep going down to a extremely low level during freeway driving, thus the yellow light will appear on the dash board, once this happens, the car will bump severely just like no suspension, and it won't raise to even level 1 by itself or manually, the light will flash all the time at level 1. The only will to bring it back to normal level is to drive off freeway and restart the engine. However, if I don't go to freeway, I have no problem under local driving condition.

GTA_Driver

Sounds like your air suspension module is done. If you cut the right wire to disable speed reading to the module, I suspect it will shut down the system and will be inoperable. Only so long you can drive before the system releases all air (it will happen eventually).

Try finding another used module. Bryan @ audis4parts.com may have some for a decent price.

PetrolBear

"The main problem is that the car will not stay at level 1 but keep going down to a extremely low level during freeway driving, thus the yellow light will appear on the dash board, once this happens, the car will bump severely just like no suspension, and it won't raise to even level 1 by itself or manually, the light will flash all the time at level 1. The only will to bring it back to normal level is to drive off freeway and restart the engine. "

Sounds interesting!
Question: all four corner exceeds level 1 or only 1-2 corner/s?

In case only the front two ones drop down (which is hardly to recognize and differ from all four corner whilst driving by 130km/h) it is simply about leaking air bags on the front. When I bought my car the same happened at the driveway. In manual mode I switched to Level 1 at 120. In my a** some kind of tdi something was pushing from the back. Then I gave full throttle, in some seconds exceeding 100 mph and leaving the TDI ritter stranded... then the wheels hit some pothole. Result: due to springing in, the (anyway existing) leaky point opened up for a moment and I lost the nose level because the pump was unable to refill at such pace. I parked out, waited and could hardly pump up (big leaks on both).

Just test it again to be sure.

Leondrew

The front part drop lower than the rear part when that happens. I guess the small leaks in the two front air springs will become important at high speed so that it cannot sustain the car body while it does in stationary. It this true, removing speed input signal may not help.

Leondrew

I think the control module is still good. I did't cut it until yesterday, and the car seemed stronger than when the wire was not cut, it stayed at level 2 (dropped from level 3) for a relatively long time until I purposely increased the speed to about 80 MPH. Two possibilities are: having cut wrong wire or the leaks become severer at this speed.

PetrolBear

Air leak does not depend on speed but does depend on level. Basically, at level 1 and 2 is worse than is 3. In case it drops any corner or nose at level 1, it can still hold the 2 and the 3, or if drops the nose from L2 overnight, parkint at L3 stays OK for days. It is connected with the rubber air bag folding in structure (see some pictures about - link socks folding in each other) Leaks happen mostly at the height on which the car moved to most. Usually level 1 and 2.

Romario

Sorry for my English! But Í'll try!
I've understood your issue. Problem is humidity and dirt inside pneumatic valve module installed near air compressor and issue come when temperature outside near of "0" degrees by celsius.
You need to provide "deep maintenence". Remove air compressor and overhauling drier-filter. It is containing silicagel inside. Impregnated of water it is working like restrictor for compressor. New silicagel would be nice but anneal also possible.
Second step - necessary to add pneumatics antifreeze Wabco in a pneumatic reciever which installed left side of laggage compartment. Antifreeze can help you to dry system inside.
Also would be better if you soak valve module in antifreeze.
If problem doesn't neglected long time all listed operation can help restore working condition.
I've expirience on previous Allroad with same operations. It was restore condition of air suspension, but I've requested new valve module and replaced it after two months.

Romario

This phrase is the same diagnose which I had in past.
It is your root cause
http://www.jimellisaudiparts.com/pro...4F0616013.html