Hi there I have a 540i 2000 which has just gone through its MOT

, and the guy who did the test advised me that a sensor on the front o/s was broken. I think its a xenon load/height sensors as the car has factory fitted Xenon lights. Can any one point me in the right direction as to wether this is a complete unit or can you buy seperate pieces for it? It appears the the arm connecting it to the top section has come off. Sorry if this sounds a bit vague but I have not had time to go underneath and look as yet always dark when I get home from work. Hope you can help many thanks in anticipation Trev