Had the same issue with mine, got in the car one afternoon, popped it in to reverse and got the one long beep followed by non-working PDC...


To this day I have no idea how it happened but when I inspected each sensor I found my passenger side front had a huge scratch across the face of it, nothing on the bumper at all, directly on the face of the sensor itself and to this day mine remain in fault mode because I refuse to take the bumper off to replace that sensor. (Though when I had my fog lights out to replace the bulbs the other day I got a hair-brained idea that I still need to go back and check out a bit more.)


Something you can try, and it's a long shot, but my wifes care will get a film on her sensors, kind of like when a headlight fogs up, and every now and then I'll take a little bit of alcohol and clean each sensor really well, fixes hers right up!