Mercedes Key Battery
 

Our 2019 Mercedes key battery needs to be replaced. It a CR 2025 3v battery. No problem, I have them on hand. Only problem is that in 2 weeks I got the same message that the battery needs replacing. I had this problem before and the dealer gave me one of their batteries, a Panasonic CR 2025 Industrial. I tried to find this battery on-line, but no luck, hence the reason I tried one of my CR 2025 batteries again. I did test the batteries I have and the Panasonic battery. Both test fine. Anyone have a similar experience and have a fix? Otherwise, back to the dealer I suppose. Thanks!

I did both of my Civic's fobs a couple weeks ago. They were three years old and I didn't want to wait until possibly dead.
Went easy and no message...same battery Duracell CR 2025 (or was it 2032..not sure)

I have noticed the batteries with the coating to make them taste sour to kids who may inject them can be a little finicky.

The coating interferes with the electrical contact. I have to and them down a little to remove the sour coat and insure a good contact.

Duracell uses this anti swallowing coating, not sure about Panasonic.
Just a thought

Replace the battery and throw the fob in the fob-receptacle in your next drive. Sometimes our 2019 sprinter gives weird fob-battery messages and this "might have" helped. I also recently had some weird screen-entertainment behavior lately and did a soft-reset of the screen and entertainment system and it cleared up some sketchy behavior.

Not all of these batteries are created equal.
I’ve had them not last more than a week in things like AirTags and digital thermometers.

Is there a reset procedure for the fob, sequence of button pushes that tells it the fob is the right one?

I think the miata has something like that