W211 Key Fob Not Working
Anyone have any ideas?
Neither of my two key fobs work, and stopped working at the same time. Both were working up until a month ago when I noticed my main key fob stopped lighting up when the buttons were pressed and obviously the doors stopped locking/unlocking. I replaced the batteries and that fixed the problem.
About a week later, the same issue started to occur, the key car would not respond when I pressed the buttons on the key fob. The lights on both fobs do come on when the buttons are pressed and one has very new batteries.
I replaced the #8 fuse (7.5 amp) for the antenna module. This did not help.
The key fob does still work when inserted in the ignition to start the car.
My AM radio signal does not seem to be affected.
Some background:
Several months ago I replaced the starter and fuel injectors. It left me with a red "visit workshop" malfunction notification with a picture of the battery. I figured it had something to with the battery being taken out in order to get to the starter and that the computer needed to be reset or reprogrammed somehow. I have not wanted to take it to the dealer so I have been avoiding it since it did not seem to affect the functionality of the car. I had been living with that malfunction for several months before the key fob issue started.
Seems like a sensor issue in the car since the problem is with both of my key fobs. Any help is appreciated.




Most common failure point is the harness on the left side of the trunk hinge; the wires flex and break. Very common and multiple posts on this. I repaired mine with a longer piece of wire a few months ago. Just open the harness and you'll find the broken wire.
Most common failure point is the harness on the left side of the trunk hinge; the wires flex and break. Very common and multiple posts on this. I repaired mine with a longer piece of wire a few months ago. Just open the harness and you'll find the broken wire.



