Hello and welcome.
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this warning is not specific and is only intended to inform the driver that a fault is present. this warning does not aid in trouble shooting in any way, it simply means there is a problem with the air suspension.
there are many things which can cause this - a failure of the control module for the suspension, failure of a sensor, failure of the compressor, and air spring or other component in the system.
the good news is, when this warning comes on, the car's computer records a record of the problem in its fault memory, and these fault logs can be read out using proper diagnostic equipment
at this time, a fault scan is the next/only step in diagnosing this issue. you will need to use a main dealer or BMW specialist shop as very specific equipment is required to carry out these fault scans.
Please let me know if you have further questions. Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you. Best wishes with your repairs.