Self Leveling Suspention

Hi All, I purchased a 2001 X5 4.4i three months back. I noticed that the rear of the vehicle was lower than the front but appeared to drive fine. Three days ago I pulled away a bit faster than usual. "Self Levelig Suspention" appeared on the cluster. I pulled over switched the vehicle off, started again and after a few minutes the warning re appeared. I have not heard any pump or noticed any variation in ride hight since purchasing the vehicle. Could anyone please advise as to where I should start to fix this problem.
Many thanks Sean

The most common problem is leaking air springs. The usually crack over time. You can spray soapy water around the whole air spring and look for bubbles. If you are certain they are not leaking, you may have a failing ehc compressor, or in rare cases and bad ehc control module. Someone with a bmw scan tool should check for faults