I don't think it's a dodgy sensor - it sounds like a harness or module problem. Hence why I say you could try swapping out sensors blindly (as you cant determine which if any is faulty) but I think it would be a waste of money.

__________________
'11 xDrive40d M Sport - 4-zone climate - Active cruise control - top view - side view - massaging/heated/ventilated seats - Powered bootlid - Comfort Access - BMW Advanced loudspeaker system - Rear side windows sunblinds - Adaptive headlights - Soft close doors - comfort seats - DAB digital radio - Panoramic glass sunroof - folding mirrors - High beam assistant - Head up display - Speed limit display - Lane departure warning system - 7 Seats - Digital TV - Internter - apps - USB