Thanks Huckster for your reply tried WD40 and locking/unlocking but still no luck with back door.was at trowbridge earlier and was on way back to car pressed remote to undo all doors and back one then unlocked.but then went to lock doors and all of them did except back door again...will sort it i think before long by taking it to friend i know got to be a simple thin like a wire a bit loose..cheers John

I have had this happen on my Ford Focus and it still plays up on occasions. I just sprayed the locks with a bit of WD40, opened/closed, locked/unlocked a few times and it seemed to cure the problem.

When I was in a local ford dealer getting it serviced, someone came in with similar lock problem. The ford service manager was advising about replacing the lock mechanism.

Dear All I have a 51 plate ford focus 1.8 TDCi hatchback lovely car but have been having a few problems of late with it.to do with the central locking on the doors.what is occuring is when using remote to lock/unlock the doors the back drivers side door will not always unlock or lock.and the same thing happens with my wifes manual key as well any ideas on this one....thanks John

P S its only on that one door the rest are fine.