98 Fiesta Driver lock stiff

If the lock won't turn in the unlock direction then the lock is worn or you have the wrong key. This is very common, any key should be able to lock the door but only the correct key should unlock, Assuming that the lock itself is turning, then there can be a problem that the link rod to the door catch has straightened out, effectively becoming longer, a quick twist with a pair of pliers cures it.

MrCheerful

A combination of both the key and lock wearing is what causes it IME. If you have another key cut from the one you have, it'll most likely unlock the door every time first time. I did it for a while on my Ka, which has the same locks AFAIK, being as it's Fiesta based.

Any ford key will lock any ford car.....it's true......but only the right key will open it !... Ford's give a hell of a lot of problems with the locks..... The tumblers in the lock wear away...... Now,,,, if you go to a dealer they can build a lock to suit your key...about £35.00... because the key usually has a PATS chip in it since 1993. If you mail me the chassis number and the Key No....... (Key No. should be like T234124 or similar) I can build you the new lock to suit your key. Or if you send me the old lock I can re-fit new tumblers in it for £10 + P&P... turn around in 24 hrs.

JK..

(PS) Henry Ford.... He made walking a pleasure.!!