E350 Keyless Go & Eco stopped working
The other day my Keyless go stopped working. It has always worked.
Door Locks: none of the doors open by the handles. There are no message on the cluster during the failed attempts. The keyfob unlocks and locks the doors.
Trunk: The trunk does not open with a foot sweep, the trunk & lock button on the trunk doesn’t work. But the trunk close without lock button on the trunk does work. The Keyfob button opens the trunk.
Ignition: the push button start does not work. There are no “key not detected” warnings. After failed push attempts it say insert key to start. Once the key is inserted it starts right up.
I also realized the ECO mode is not working. It has also worked in the past. I thought I was driving different, but I can’t get the engine to stop no matter how I push the brake at a stop.
I’m not getting any faults or warnings from the car itself. Any ideas? Thank you in advance.
the key. I just surprised that even car dealer didn't even know that the key had battery in it.
I just realised you mention you had new key battery. Make sure you got correct battery because i think at least two kind it fit and one thinner than other. The thin one will cause problem and you need to put something so it contact better. Always buy the thicker one
Last edited by andynmaas; Feb 13, 2022 at 08:45 AM.





the key. I just surprised that even car dealer didn't even know that the key had battery in it.
I just realised you mention you had new key battery. Make sure you got correct battery because i think at least two kind it fit and one thinner than other. The thin one will cause problem and you need to put something so it contact better. Always buy the thicker one
As for key fob batteries, they are designed to use the CR2025 (thinner) battery. Some people jam the CR2032 in there, but it is the wrong battery technically as CR2025 is specified on page 93 of the manual. If you bought your MB at a Ford dealer, the Manual is available at the Mercedes-Benz website.
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Looks like you guys are right! Thank you for the help. Now to get a new battery, is it true you can’t just switch out the battery yourself? Or if you do there’s a bunch of stuff you have to do aftward that is lost due to the lack of power?
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Key fob battery charge state and fit play a role in Keyless-Go function. But the non-functioning ECO Stop/Start is caused by the weak MAIN battery. Best to keep both topics separate.




Key fob battery charge state and fit play a role in Keyless-Go function. But the non-functioning ECO Stop/Start is caused by the weak MAIN battery. Best to keep both topics separate.
The key fobs function when pressing the buttons. I do not get a replace battery warning when in or near the car. Before I could touch any door and get a response. Now, no doors are responding. When I get in and press the start ignition button with my foot on the brake nothing happens. No messages nothing. Eventually it will tell me to remove start button and insert the key. The handfree trunk open and close trunk and lock button is not functioning. The colts trunk button does work.
i have replaced the battery in both key fobs with a 2025 new battery.
Last edited by smokinfish; Mar 11, 2022 at 05:35 PM.
I connected a ICarsoft MBII reader to it today and got the following fault code for keyless go B226155.
Not sure what it means other than there is a problem.


