tow bar

[stevox5]

Sounds like the wiring loom for the sensors has not been reconnected after the bumper has gone back on.there is a block connector under the black plastic boot floor panel on the drivers side held down by 3 10 mm headed plastic nuts.
This connector is for the wiring loom in the rear bumper for the rear sensors.
HTH

[UrbanFlow]

Hello mate,
I fitted my Westfalia detachable with dedicated 13pin wiring at the weekend.
(I'm putting together a photo-how-to and will post on here for those interested)
The parking sensors have to be disconnected (It's one plug) before the bumper can be removed - it may be that the fitter didn't reconnect when he put it back together.
The rear parking sensors work as normal unless you plug a trailer/bike rack/caravan electrics into the socket. Then they disable automatically.

Check yourself that the fitter reconnected correctly - the PDC connector is on the right side of the cargo area. open the hatch on the right and look inside. Here's a picture to help...