Oh, didn't realise that.
On the o/s/f and o/s/r suspension arms there is a small potentiometer connected between the lower arm and the chassis to measure the height. It clips onto the arm with a little press-on balljoint but can and does come off. You need to remove the wheels to see it and clip it back on if it's come off. My front one used to come off regularly for some reason on my e46 but not happened with my e92 or f10. Principle of operation is identical, however.
Current: 2013 F10 520d M-Sport, Professional Media, Visibility Pack, Reversing Camera, DAB
Previous: 2011 F10 520d M-Sport, 2008 320i M-Sport Coupe, 2002 325i, 2001 318i valvetronic, 1998 318i, 1996 525i, 1990 Porsche 944S2