Hi Duncan.
Sounds like you will need to remove the wheel arch liner, and the washer bottle,;) rear sensors could be a little corrosion on the spliced part of the loom, but I have also known the sensors to be dirty enough for that fault to occur, don't know why I am trying to teach a teacher
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mind this bit of info maybe good use the vanish soap bar to clean the leather seats works a treat, soft nail brush and the soap bar, wipe off excess with a damp cloth, then dry off with a clean dry cloth, leather balm after.
PS I used the scourer pad on the hard plastic of a steering wheel, so not good for leather seats.
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