Parking Sensors repair

My parking sensors stopped working, front and back, apart from a occasional useless bleep.

I noticed that one of the rear sensors was just a tiny bit misaligned, only a milimeter I guess.

So I removed the bumper.  The sensors are cylindrical and slip into a holder glued or plastic-welded to the inside of the bumper. I noticed that one side of the rectangular plate of the holder of the misalligned one, had slightly lifted away. When I pulled slightly the whole holder came away. I cleaned the surfaces, applied superglue and replaced the holder on the bumper, using the sensor to align itself in the hole. I tested it before replacing the bumper properly and was gratified to find it working, and at the front too.

A Youtube video of a bumper removal for a same-year Insignia was useless, being totally different from mine.

To remove the bumper, the rear lights must be removed, in order to be able to release the hidden clips. There are 3 plastic wing nuts holding the lights and it is necessary to be a bit brutal with the upholstery to get at them. It may not be necessary to disconnect the lamps if they are carefully hung into the boot - not really recommended - but the connectors are difficult to part. There are 3 torx screws under each wheel arch, and 3 more under the rear of the bumper. Then the bumper must be pulled out sideways on both sides to unclip the sides and the clips which were hidden by the rear lights need to be depressed to release them.  Then pull the bumper backwards. The connector for the sensors and plate lights must be parted. It slides onto a clip to stop it flailing around.

The pictures show the various clips, the sensor with its rectangular glued plate, the torx screws and their position under the wing, and the rear light with its wing nuts.