Hi I also have a GV 2007CRD, had a 2001 2.5CRD for fifteen years too :-) Front knocking is almost certainly anti roll bar bushes and or drop links... these are a very common wear out item.... if you're at all handy with the tools it's a quick & easy job. I have found that Meyle drop links are by far the best and a reasonable price at around £30 a pair, bushes are about £10 a pair. The reversing sensors can be switched off on the ovehead display/trip conputer. Are you sure that you'rs are just not switched on ? Mat