Central Locking issue
This is the first real issue I've had with the electrics since buying the car brand new in December 2008. Has anyone any ideas of the cause and is it a relatively easy fix?
Thanks




Does it lock with the rest of the doors when the speed increases from a standstill?
Or does it only fail to lock and unlock with the remote key fob?
If the problem is only with the key fob, then it is not a problem with the door actuator.
Have you scanned for codes? A scanner that can read codes from all modules is needed, not just engine and emission systems. The problem could be in the rear SAM, or the door control module (N69/1 on euro models if I read correctly), or somewhere else on the interior CAN.
The common problem is the door actuator motor. That is a doable but difficult DIY fix because the door trim, interior panel, window, window motor, structural door liner must all be removed to get to it. Almost any other cause of doors not locking or unlocking is easier to remedy. You want to be certain it’s the actuator before starting.
Here is a video of diagnosis of a W204 similar to yours (I think)
https://m.youtube.com/watch?v=3AoHgASxu5Q


