Parking assist fault

[Killerdelts]

Got this fault come on since I've had van comes on when I turn engine on reversing lights work  all sensors beep when I go near them and it makes a noise when I put in reverse  Any ideas thanks

[Killerdelts]

Just went out and cleaned all the sensors and they all bleep when I walk near back of van so nothing wrong with them but still getting parking assist faulty. only comes on once after when I put in reverse. If i take it out of reverse and put it reverse again it don't come on any ideas thanks