BACnMercedes
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May 4, 2026
- Join DateMar 2012
- LocationThe Palmetto State
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- Vehicle(s) I drive19 E63s, ‘24SQ8, wanting another gas guzzling V8
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Liked:451 Times in 311 Posts
I have a question about key fobs and car batteries for a 2010 E63
My second key fob will not work. I called the dealer and they said as long as the red light comes on on the fob then it should work. Well the keyless go, unlock or lock doors, nor the key in the ignition works. Nothing. But the red light comes on. (Yes I have changed the batteries, twice now) Any ideas what the dealer means by the red light coming on or should the fob work? (what would make a key fob go bad? It is the spare that stays in a desk drawer)
The second question is about the car battery. It seems to go dead often even after I have driven it. I had it checked and supposedly the battery is good. But I looked into buying another battery ($340) and was told MB batteries are different and I could not put in an aftermarket battery unless I "vented" it. What is that and is that true?
On a side not, I don't think the car battery is affecting the key fob because the other key fob works great.
Thanks
My second key fob will not work. I called the dealer and they said as long as the red light comes on on the fob then it should work. Well the keyless go, unlock or lock doors, nor the key in the ignition works. Nothing. But the red light comes on. (Yes I have changed the batteries, twice now) Any ideas what the dealer means by the red light coming on or should the fob work? (what would make a key fob go bad? It is the spare that stays in a desk drawer)
The second question is about the car battery. It seems to go dead often even after I have driven it. I had it checked and supposedly the battery is good. But I looked into buying another battery ($340) and was told MB batteries are different and I could not put in an aftermarket battery unless I "vented" it. What is that and is that true?
On a side not, I don't think the car battery is affecting the key fob because the other key fob works great.
Thanks
Member
I would fix the car battery issue first, then retry the fob.
New to MB, but I know the BMW M5 had a vented battery under the floor in the boot (trunk). There was a ventilation tube running from the top of the battery down and out through a hole in the floor.
All sorts of odd gremlins emerge when a battery is suboptimal.
Scott
New to MB, but I know the BMW M5 had a vented battery under the floor in the boot (trunk). There was a ventilation tube running from the top of the battery down and out through a hole in the floor.
All sorts of odd gremlins emerge when a battery is suboptimal.
Scott
these fobs suck up battery life, always changing mine
For the keyfob issue, sounds like your other remote will need to be reprogrammed to the vehicle. If the red light is coming on, that means there is sufficient voltage from the CR2025 key battery to operate the remote. Usually if the battery is low you will also get a note in the OBC display stating key battery low.
BACnMercedes
MBWorld Fanatic!
close
May 4, 2026
- Join DateMar 2012
- LocationThe Palmetto State
- Posts:2,364
-
iTrader Positive Feedback0
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iTrader Feedback Score(0)
- Vehicle(s) I drive19 E63s, ‘24SQ8, wanting another gas guzzling V8
-
Likes:491
-
Liked:451 Times in 311 Posts
Thanks. I think I will break down and just buy a new battery and start there. I still cannot figure out that dang key fob though. I'll probably have to buy a new one there also.
Member
You can absolutely use an aftermarket battery. The dealer is employing scare tactics. Any similar sized group battery and cold cranking amp will work. Many are vented as well. I know a few folks that are using non-Mercedes batteries just fine.
