Morning Markus
Sorry that isn't a code it is only the cars display warning.
To begin with have the fuses been checked? Check the fuses if they are OK then you need a proper diagnostic session to identify the problem.
I have seen 1 failed trailer control unit and 2 failed gears in the folding motors (one on my own X5)
All 3 I was able to fix by sourcing replacement a replacement control unit, and stripping and rebuilding the folding motors.
Dave