Hi, I have a problem with the central locking on my 2006 fiesta. 

If I press the lock button twice which activates the deadlocks, both doors lock. But when I unlock the doors again the passenger side stays deadlocked and cannot be opened, even using the handle inside.

Simple fix is to only press the lock button once, but occasionally I accidentally hit it twice, or last night my partner used the car and forgot about the problem. 

Sometimes I can get the passenger door to unlock again after a few (dozen) goes with the unlock button, other times it can be a few days. Just concerned that its going to stay permanently locked one of these days.

I've also noticed that when pressing the lock button once, the passenger's internal handle isn't going fully into the locked position although the door is locked from the outside. 

don't know for sure but it sounds to me like it might need the inner door panels taking off and all the lock mechanism bits lubricated inside the doors. 

I took everything to pieces and cleaned and lubricated but no change. I got a used mechinisim on ebay for £14 from what turns out to be a slightly older model. Probably pre facelift. Some of the pins in the plug were in different locations and it had the extra lever for a key to operate from outside. But surprisingly it all fitted and locks/unlocks perfectly. Just doesn't deadlock anymore. 

 

To be honest that suites me as the same problem can't reoccur. Absolute PITA of a job to replace but was easier the 2nd time.