XSeries-forum

Update. I have finally got round to getting the car in the air and looking at the sensor and arms. Nothing was broken arms on both sides were folded the same way. The ball joints on the arms were clogged up with sh*t so I remove the sensor and arm from both side and cleaned the arms to free them up. I've sprayed all the contacts with switch cleaner, although they didn't appear dirty at all, and put it all back together.
I then did a diagnostic check and this time it said fault on both left and right rear, is this because it had been disconnected ? Anyway I've cleared the fault and will take it for a drive today and update later.

Yes generally speaking if you disconnect stuff it induces a fault code which needs cleared.

Update. Drove 5 miles warning back on dash.

You can get of e-bay from £25 upwards, obviously second hand and a risk you take or go to dealers and probably pay £150 +, don't know I haven't looked. Perhaps someone knows a cheaper option. I'd go with the cheap e-bay option because it's a low price and will confirm that is the problem. It could be a wiring issue, have you traced the wiring as far as possible, it does get brittle in that area.

Thanks for that. Checked the wiring yesterday  and all seems intact.
Have just replaced the sensor and reset the fault code. Will drive
to work tomorrow and see what happens

Update.
Done a few miles now. Right hand side has gone back up to normal level and no warnings on dash.

Glad you got it sorted.

This post saved me some time for a similar issue being the battery at fault.

Nice to see a post finished off with a positive result