I have a X5 4.8is with the famous two axle air suspension. My issue is not the normal compressor, leaking bags or control unit errors.

The problem with the car is that when parked the front drops about 10-15 mm and when start it wakes up to normal height (even if parked for 15 minutes).

I opened up the concentrator tank, checked the pipe links with soapy water, as well as the pressure regulator - no leaks. It also goes into air suspension inactive mode from time to time and then it has to be reset. No major errors on the computer when reset.

How do i fix this?

Any suggestions?