Hello, I have a problem with my Ford Fiesta MK6, year of manufacture 2003. I have a central locking fault and it shows that it keeps locking and unlocking the car by itself. The wiring seems to be fine. I think I found the cause and it is something with the right front lock. I bought a new front lock for the left side and when I connected it to the left front, the problem persisted, but when I connected the left front lock to the right front, everything works immediately 😀. The problem is, however, that I can't get a new right front lock. What could be causing this in the lock? Can I fix it?

Before you changed anything, did you have a door open alarm for either of the front doors ?  Or did the alarm go off occasionally ?  If the GEM thinks a front door is open, then you will get that problem with the locking/unlocking cycling.

The micro switches in the door locks are a known problem, I have changed three locks in our Fusion, and one in our two door Fiesta.

no the door open alarm did not go off. can the microswitch be replaced after opening the lock? can I measure if the microswitch is good?

The door ajar microswitches are what triggers the alarm, so perhaps the lock cycling might be the driver's door "Locked or Unlocked Microswitch".  This is not the ajar indication.

Clutching at straws, disconnect the battery, and operate the driver's door lock by turning the key firmly, ie locking and unlocking, about a dozen times.  If you are lucky, this might clean up the contacts.  This "solved" a problem I had with the internal boot release........

Typical door lock image attached - difficult to access in the first place, and the microswitches are inaccessible, and a new doorlock is a prohibitive price.  You might be able to check if the switches work from the GEM plugs, without removing the lock, but not tried it myself.

And you need to take off this panel:

And then this panel:

Fusion rear door shown, but Fiesta fronts similar but bigger with electric windows !

If you do access the doorlock motors, clean the internal window slide, and put on some fresh grease. After 12 years, the grease is probably hard.