When I purchased the FF there was a problem with the pdc and I replaced the rear loom in the bumper and since then they've worked fine for 9 months, the other day they were working when I parked it, got in it today and soon as put it in Reverse peep peep beeeeeeeeep as if it was up against a wall? Cleaned each sensor ( even though they were clean) no difference, listen to each sensor and they are all ticking.
Noticed if I turned it off and moved forward the front ones were working properly? Looks like it's the rears that are giving the fault, anyone any suggestions? Which is the control unit? Offside rear compartment in boot behind something else? 3 plugs going into top?..
cheers.

Could be the Bcu - this is just one of the functions it controls. My pdc set off the "not working" alarm sound on start up but work fine 2 mins down the road. New bcu required!

Bcu?...?

Body control unit -it's under the passenger seat. If you change it you will need to get the new one re-coded to your car (main stealer job?)

Do a search. Here as there is lots of info and pics.

Replacing my BCU - to cure intermittent rear door unlocking and heavy steering problems - also cured an intermittent problem with my rear parking sensors which I had not associated with the BCU.
See http://www.fullfatrr.com/forum/topic40009.html (in Wiki)

 It's "bébéchoon", ackcherly, with accents. 'Steve' to my chums.
20 years ownership of Solihull products, ALL GONE NOW, sniff!
Current motor: Suzuki S-Cross 4WD auto, 1.4 petrol. Oh so reliable! 7 years now and no problems. Oh, all right then, a leaking shocker replaced under guarantee.
Previous:
TD6 HSE L322 Auto FF
2.5 TDi 4-door Classic
Disco II
And my 1st Rangie: in 1995, a 2-door VM 2.5 diesel Classic
Not to mention the Lada Niva before those. (I said not to mention it!)

Put the CTec on for a bit and thought I'd do a disconnect on the battery while I was there ( it used to cure things on the BMW 750i) and lo and behold the PDC has started working again, let's hope it stays working 😀