When I put the car into reverse one of the sensors stays on (red) on the screen as if something is behind me, I done it again an hour later and it worked fine, could someone of knocked the sensor on the bumper??

It's got water in it.

Common problem and soon corrects itself.

Only one of mine does this (edit: out of 6 sensors), always in the rain. I have front and rear PDC. It is annoying as it is a distraction when you are listening to a solid tone - need to mute it. I think the basecoat and lacquer might be a touch too thick on my one sensor, which when water is sitting on top of it as well causes it to become unserviceable.

 

Edit: I really should try and procure a new one and respray to try and resolve it. 

Edited 1 February, 20179 yr by TheClient