Please help with Central Locking

[Buxx1]

for a long time when pressing the unlock on the fob twice all the cars doors opened but the passenger door. The passenger door only unlocked by manually opening the door from the inside.

Yesterday, somehow, several times the passenger door unlocked with the rest of the car doors. So it was working. I deadlocked and unlocked to check that this wasn't just a one off and it was working to my delight.

This morning it's stopped again

Any experts out there that can explain what's happening please.

Thank you

 

[SootySport]

Solenoid is sticking or on it's way out. Bet when you take things apart to investigate it'll work everytime, in which case I would fit a new solenoid and when fitting it lube up the rest of the door lock mechanism.