Sorry to do this one again,  I've read various posts here on this but I'm looking to avoid unnecessary labour time and I'm losing the power of logic. Using the main key or the non buttoned stand-by key, makes no difference to the fault itself. One intermittent fault:- lock the car from outside, doors won't stay locked. Happens say 40% of the time. The second fault isn't intermittent now but gradually got worse over last 9 months....get in the car, don't activate child locks. Only the driver is in the car. Sign appears on dash panel..."passenger door open", but the door isn't open. Open the front passenger door from inside, close it. Sign disappears after the first attempt, always and you never have to open the two rear passenger doors to clear this fault. I'd love to think something is sticking mechanically but that'd be too simple?

I am "happy" to go to a breaker's and get a nearside lock out and risk it for a biscuit. But before I do this, and then do the same with the donee car, does anyone have any other things I could try please? It seems the front passenger lock could be to blame but I am happy to be corrected on this. The only other thing I've done is press unlock and lock buttons simultaneously for 5 seconds on the main key, no improvement. I've used jolly old wd 40 but I think this was wishful thinking.

One other thing - you never return to the car later to find it has "unlocked itself".

Anything else I could try please before a day at the breaker's ?

2008 Mk 6 1.4 Zetec

 

 

It sounds as though the passenger's door is trying to lock but isn't recognising that it has done which means the car thinks a door is open so it will not lock. Busted wires in the door jamb are often to blame so trace them through one by one. I usually use two needles on wires to pierce the insulation of each wire between the door lock electronics and the loom at the door pillar, checking for breaks with a meter and a disconnected battery. A circuit diagram will help but do this first because it is necessary to confirm that the wiring is good before buying a lock which, if it makes no difference would be maddening.

The fault is the microswitch in the passenger door lock is sticking.

The car will not lock (or will unlock) if the microswitch is in the open circuit possition. You could remove the door lock and strip it and clean the microswitch, but it is a pain to do. probably better just to buy a second hand lock.