2003 Mercedes E320 4Matic sedan. Had been working fine, but the battery died. After replacing it, it worked fine for a day or so, but had to replace a sensor because it wasn't starting properly. The fob stopped working as well.

Changed the fob batteries, but the doors won't unlock. Don't see the LED circle lighting up, but then again, perhaps it never did. So basically I have to unlock the door with the blade key, but the fob works in the ignition turning on.

Is the fob salvageable? I know it's old, but it's odd that it died right after the battery was replaced. Is it possible it needs to be merely programmed to unlock the car, etc? Or do I have to take it to the dealership and pay $200 for a new fob?

Thanks for any advice out there.

 

There's a sequence to re-sync the fob to the car. Put a new battery in the fob just to be sure and then re-sync with the car. Owner's manual tells you how it pay the dealer. A new fob is around $600 unfortunately but I doubt that's the problem.

 

Thanks for the reply. What is the sequence to sync it to the car? Sounds like you are saying the manual only tells you to go to the dealer. Thanks.

 

You don't have to go to the dealer. The manual should clearly outline the procedure, I just don't remember it now and it varies if the car had keyless go or not. Follow instructions and you should be OK.

 

if fob starts the car then it should open door, if not the fob shell is bad, the batteries not connecting properly.... happens especially on the old black fobs...... make sure the battery pins bent far enough to reach the PCB board in the remote shell.... the red light suppose to blink.... also make sure the batteries inserted properly....

 

I assume no second key, additional to consider check fuse f8 (antenna amplifier) @ rear SAM. If fine you can check internal board for any obvious problems.