Central locking issue : 

Doors will not stay locked when you press the key fob lock button. 

They lock then unlock. All doors except rear passenger door will lock manually from inside .

"Drivers Door Open" Red light displayed on dash when driving. 

Any ideas please ? 

The small microswitch inside the drivers door lock is broken or stuck in the door open position.

The central locking will lock and then unlock the doors while this fault exsists. The microswitch is deep inside the door lock and not that easy to get at. Best action is to buy a secondhand lock from a scrapyard (normally about £20).

It takes about 1 hour to strip the door panel off remove and replace the lock and put it all back together.

Does that mean another key ? 

Is there a chance of getting any WD40 or such like in there ?

You need to replace the Door Lock, (the latch) not the door key barrel.

Very little to no chance with the WD40 unless you remove the door lock from the door, then open it up (lots of springs and stuff will pop out) then give the little microswitch a spray.

This ? 

 

https://www.ebay.co.uk/itm/2006-FORD-FIESTA-MK6-DRIVERS-FRONT-DOOR-LOCK-CATCH-ACTUATOR-SOLENOID-/154659452573?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=710-127635-2958-0

No. That is the central locking actuator. 

You want the door latch. 

 

Do you know what it looks like ? 

 

.

This is a Fusion one, Fiesta probably identical or similar.  Micro switch araldited in place on the Fusion, underneath the metal plate,

6 minutes ago, johnboy1958 said:

Not that easy these days, most scrap yards have closed down

But that post was 2 years ago 🤣

Never mind here's a scrapyard in Peterlee County Durham.  https://www.ne-motorsalvage.co.uk/contact-us/