Hi just some info that might come in handy I had the rear camera inoperative and a load bleep when you select reverse.
Most people said the water gets in and you need to get a new camera.
I took the camera out and it was fine no signs of water damage anywhere.
The problem was not with the camera but with 2 of the parking sensors on the bumper so I took the bumper off and started testing the sensors and two were faulty.
Purchased 2 new ones from ebay for under £20 posted fitted them and now everything is working as it should.
Just thought this might be useful to someone with the same problem.

Hi Barry,

When you say inoperative - do you mean didn't come on, but screen went black or nil effect whatsover on the screen?

Hi you can hear a high-pitched tone and it says rear cameras inoperative with a black screen.

Hi Barry-I have the same problem. How did you test the sensors?