I tried this on the Tech Help section but got no answers so I'll try it here . . .

Our '96 E300D (W210, OM606NA) has two identical lock/alarm key fobs – the "switchblade" kind. One works fine, the other keeps losing its synchronization and then won't lock/unlock (the metal key part always works, of course). I know the fob has stopped working when the red/green lights on the rearview mirror don't flash for locked or unlocked.

When the "bad" one loses sync, I follow the procedure in the owner's manual and then it works again for awhile. I swapped the pair of 3V batteries between the two fobs but that didn't help. I also checked them with a meter, they test good. The "battery test" (press the button for 1+ seconds and the red LED will blink) works.

This is not a major problem since we have a second fob and since the metal key works regardless; nonetheless it would be nice to have this thing stay in sync without buying another as they are expensive ($140 last time I checked).

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Probably been banged around over the years and the solder joints cracked. This happened to my Clifford alarm remote on my truck. I had to take it apart and re-solder all the joints. It's been perfect since.

As far as your remote key is concerned, I have no idea how to get into it...

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-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250