There may be something wrong with the control unit and the only replaceable part is the relay that controls the pump. P/N 61-36-8-373-700. The system is readable for faults with the BMW proprietary software, you may have to seek out someone who has access to it.
December, 31, 2010 AT 4:44 AM
Check the fuse for the air suspension. Fuse #87 in the trunk fuse box. I replace mine and the problem went away. Good Luck