Hey all,
My central locking system works well after I replaced the pump, but now the fuel filler door will sometimes not unlock, especially in cold weather. Is it common for the actuator to freeze in cold weather? Also, if I unlock the car from the trunk, only the trunk unlocks and the factory alarm does not deactivate...what part should I replace for that? Thanks in advance.

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1985 190E 2.3-16 Euro

My fuel filler lock does not operate every time I need it to. I have had to access through the trunk several times. Mine may just need to be lubed. Will be interested to see what others have to say.

Does the trunk unlock all the doors sometimes, or doesnt work all the time???

If it is acting like the fuel filler door i would check the vaccum lines.. make sure they arent blocked, or if they are tightly connected. I had this problem in my 190E, needless to say i checked the vaccum line and it wasent pushed in,, i pushed it in and never had a problem since..

1. My 190E fuel filler door occasionally ceases but will eventually open when left for an hour so...why?
2. Also, from front passenger side, central locking will work on all; but from driver side, will lock all but not open all, only itself...why?

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'92 190E 1.8

Again, check all your vaccum lines,, this is how the system is operated.. and if there is poor vacuum, then it will not work right

So does anyone know if I should replace the lock itself for the trunk or the actuator with the metal rod in order to fix the problem of the trunk not locking and unlocking the whole car?

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1985 190E 2.3-16 Euro

It's probably just the actuator, they behave exactlly like you describe, especially in cold weather.
I had the same problem with one door, where it would lock but not unlock, especially in cold weather.