Key Fob
Thread Starter
Member
Joined: Mar 2013
Posts: 85
Likes: 15
From: North Carolina
2011 E350, 2015 E350 Sport
Key Fob
Have a 2015 E350 and got a message that key not recognized and car will not start .Replaced the battery with a new CR2025 and while the doors and windows work the car will not start. Tried doing a resync of the new fob with no results. Car starts with key inserted but will not start remotely. Did a search with no result on how to pair ---- looked in the owners manual ----nothing .
So i need an input on how to solve this...Thanks
So i need an input on how to solve this...Thanks
Out Of Control!!
Joined: Apr 2019
Posts: 12,191
Likes: 6,888
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
PARTIALLY WORKING KEYFOB
Have a 2015 E350 and got a message that key not recognized and car will not start .Replaced the battery with a new CR2025 and while the doors and windows work the car will not start. Tried doing a resync of the new fob with no results. Car starts with key inserted but will not start remotely. Did a search with no result on how to pair ---- looked in the owners manual ----nothing .
So i need an input on how to solve this...Thanks
So i need an input on how to solve this...Thanks
The car is acting up but the keyfob is working. Good!
Some of your chassis modules are begining to communicate unreliably (solderless KeylessG). This impacts the keyfob functionalities.
Your local MB Dealer will be able to restore much needed key reliability - Ask to get batteries inspected at this time before winter season in case of battery drain without trickle charger.
Last edited by CaliBenzDriver; Oct 24, 2025 at 08:45 PM.
Senior Member
Joined: Apr 2016
Posts: 461
Likes: 158
From: Phoenix, AZ
2016 E350 Sport 2WD
Check the voltage of your newly installed battery. My wife's fob doesn't 'like' voltage below about 2.95 volts and sometimes gives her problems. Changing the battery to one over 3.0 volts solves the problem for a while. Try locking and unlocking your door a couple of times and see if any difference. About a year ago, I drove about a mile to the Insurance office, locked the car, did the insurance business, and when I came back out, the car door would not unlock. Try as I might, it just would not unlock. So I walked home, got my wife's fob, walked back to the insurance office, and opened the door, started it, drove home. After I got home, I tried my fog again and the door unlocked,. Tried that successfully probably 10 times and it never faIled, So ?? sometimes, cause of the problem is unknown or undiscovered.
Is yours Keyless Go?
Is yours Keyless Go?
Last edited by Sunnyslope48; Oct 24, 2025 at 11:12 PM.
Thread Starter
Member
Joined: Mar 2013
Posts: 85
Likes: 15
From: North Carolina
2011 E350, 2015 E350 Sport
Your working keyfob quit being recognized to start the car unless inserted in keyslot. New battery allows control of doors and windows.
The car is acting up but the keyfob is working. Good!
Some of your chassis modules are begining to communicate unreliably (solderless KeylessG). This impacts the keyfob functionalities.
Your local MB Dealer will be able to restore much needed key reliability - Ask to get batteries inspected at this time before winter season in case of battery drain without trickle charger.
The car is acting up but the keyfob is working. Good!
Some of your chassis modules are begining to communicate unreliably (solderless KeylessG). This impacts the keyfob functionalities.
Your local MB Dealer will be able to restore much needed key reliability - Ask to get batteries inspected at this time before winter season in case of battery drain without trickle charger.
Out Of Control!!
Joined: Apr 2019
Posts: 12,191
Likes: 6,888
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
I was referring to CAN-B Modules: keylessG + CGW... A chassis scan may revel what disruptions are active.
This is when MB Dealers network can shine to sort out this issue.
MBWorld Fanatic!
Joined: Dec 2011
Posts: 4,393
Likes: 957
W212 FL
A simple trick :
Get in the car
Press unlock button once
Press lock button once
Press unlock button once
After all those 3 things above , you should be seeing the gauge cluster flashing as I recall .
The car should start .
Mine acted same way but it looks like it fixed itself without doing anything extra thing
Get in the car
Press unlock button once
Press lock button once
Press unlock button once
After all those 3 things above , you should be seeing the gauge cluster flashing as I recall .
The car should start .
Mine acted same way but it looks like it fixed itself without doing anything extra thing
Thread Starter
Member
Joined: Mar 2013
Posts: 85
Likes: 15
From: North Carolina
2011 E350, 2015 E350 Sport
A simple trick :
Get in the car
Press unlock button once
Press lock button once
Press unlock button once
After all those 3 things above , you should be seeing the gauge cluster flashing as I recall .
The car should start .
Mine acted same way but it looks like it fixed itself without doing anything extra thing
Get in the car
Press unlock button once
Press lock button once
Press unlock button once
After all those 3 things above , you should be seeing the gauge cluster flashing as I recall .
The car should start .
Mine acted same way but it looks like it fixed itself without doing anything extra thing
Nope....did not work. It did set alarm which went off when I exited car. Note the instruments lights come on when i enter the car and car starts with key (a good thing) However the car does not detect the key for starting and remote door opening . All other functions using the key appear normal. I may try my indy car next OR a locksmith....last resort will be dealer $$$.
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Thread Starter
Member
Joined: Mar 2013
Posts: 85
Likes: 15
From: North Carolina
2011 E350, 2015 E350 Sport
Well..I seem to up against a wall with the smart key issue. Can anyone tell me where the smart key antenna would be located ? I cannot find a definitive location online .
Thanks for any help.
Thanks for any help.
Out Of Control!!
Joined: Apr 2019
Posts: 12,191
Likes: 6,888
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
wrong track
Consider the replies that were provided by members to help you.
