Key fob battery?

Hi all, when getting a new key today, the tech said "hmmm, the button doesn't seem like it's working too good, may need a new battery". Can I pop these keys open and replace them? Doesn't need to get reprogrammed? Is it a 2032 battery? It's a 2014 C. It looks like a regular key, not a switchblade type key.

 

Yes! But it was the old key that came with the used car.

Thanks!!! It does look like 2032's and I remember ordering a dozen or so from Ebay a few years ago. Should be in my freezer

 

Oh yes, it is working, its the one the key guy made a copy from. So the original old one he said "hmm, seems kinda week". So I'll try putting a new 2032 in it tonight.

Found the manual online, shows how to open the key, and then remove the module, and then open that up.

 

Welp, that didn't work. Just opened it up and saw a 2016 battery in it. I thought maybe that was wrong but I opened the manual.pdf and it said "keys without smart key system uses 2016 and keys with smart key system uses 2032's. So off tomorrow to get a 2016

 

Got a new multimeter and battery was reading like 2.5 so I replaced it. Reading 2.9. So all good for a while.

 

That's good. I should check it again. I just got this brand new multimeter so maybe I was holding it funny. I'll try with the other one that's in the package. It should be reading at least 3.0 right?