Mercedes c class central locking

[rogerfromnorwich]

Wondered if anyone can help. I have a 10 year old c class with central locking problems. I think it is in the passenger door as when driving off the car should automatically lock all doors, the lock on the front passenger door goes up and down fast. Then when I get out and lock the doors this door does not lock.

Any suggestions please?

 

[Belle427]

90% of central locking problems are either the door actuator itself or the wiring that runs from the door into the car near the hinges breaking down.
First thing to do is lubricate the door lock mechanism liberally in case its sticking, opening and closing the door as you do so.
You may even need to remove the door panel to gain better access to linkages etc.