Park Assist

Hi Gang
My 03 X5 has an intermitent issue with the park assist. sometimes it works, both front and back, most of the times it gives a long beep then the right side mirror starts moving up and down but regardless of how close we get to something it doesn't speed up the beeps.
I know on my other car if one of the sensors was pooched none of them work, you could check the sensors by having the car in reverse and have someone listen to each sensor, the one not buzzing was pooched. None of mine buzz so......

Thoughts ideas?

My x5 has the same damn problem. the only thing i can think of is mine has a Halls towbar fitted and the trailer plug wiring was added to stock so maybe its messing with voltages?

Forget the Hi Tech parking assist and go with a Low tech solution, if you can't park a car. LOL