draught

Hi Guys
Maybe this has been covered before but I couldn't find it on any of the threads.

I have an A5 2013 with rear parking assist and I damaged the rear bumper so I replaced the parking sensor with one from an a6 but it was the wrong number and nothing worked, so I bought one new on ebay which was the same number and is ticking so it is working fine.
My problem is that when I put the car into reverse I get the normal beep then followed by a constant long beep.
I switch on the ignition and put the car in reverse and release the electric brake , I select settings button on the screen and move the curser to parking assistance.
It changes from orange to white and gives me the option to adjust volume and frequency, then I go to the back and hold my hand over each sensor individually, they all work fine.
So after this, I start the car and every thing is fine until I put it in reverse (automatic)and let it move, as soon as it moves the parking assistance writing on the screen goes gray and can not be selected and the sensors do not work.
When I take it out of reverse the writing goes white again until I put it in forward and same story.
I've checked for damaged wires, bad connectors and all that but I think it is a coding issue, there are no fault codes showing up on my diagnostics unit (delphi) though so I don't know where to look.
I have tried to access hidden menu too on this car but it will not open

snagitseven

You need to run a scan with VCDS or similar OBDII tool.

draught

I have run a scan on a delphi diagnostics obd11 tool but not showing a fault so I'm wondering is it a module that needs to be recoded.