I recently got the “Replace Battery in Key Remote” message popping up on my MID. Needless to say, when I changed the battery, I replaced it with the same type (CR2032), though when I popped in the replacement (one of 4 on a blister pack that I had lying around…doubtless from some electronics I had previously bought), it seemed slightly thinner that the old battery. I assumed I was mistaken, and spoke with a guy that sells these batteries, and he confirmed that the dimensions should all be the same.

In any event, I immediately noticed that the remote didn’t seem to work as well as before. It still unlocked when I put my hand in the handle, but it almost seemd like there was an additional delay of a fraction of a second. Chalked it up to my imagination, especially since I wasn’t getting any “replace” message on my MID.

But then the other night, when I jumped into my car, it wouldn’t start unless I put the remote in the slot. Then yesterday, I got out of the car with the engine running, herd the characteristic multiple beep to tell me that I had the key in my pocket, but when I got back in the car, the MID said “Unable to Detect Key”.

I’ll sub out the new battery and replace tonight, but it seems the moral of the story is that not all batteries are alike.

 

Personally I don't think its a battery thing. I've had problems with my car randomly displaying the replace battery message and then going away after a couple of days. Sometimes the remote stops being detected, and then is fine a day or two later. Even after replacing the battery, the message starts coming up again after a while. I even had my fob replaced under warranty, but it still does it here and there. Somebody else on this forum reported something similar with theirs. I think there is a design flaw or some faulty component causing this.

edit: The other thread is here

 

Seems it is the battery. After the issues I was having with the first replacement, I subbed in another battery, off-brand, but straight from the blister pack. Came with a camcorder that I bought a year ago. Shelf life on these things is generally about ten years, and this was another CR2032, but it didn't work at all.

So, I bought a Duracell replacement (DL2032), and it works like the original. So if anyone is experiencing these sorts of problems with their fob, even if the battery is appropriately charged, it may simply be that the fob is looking for a name-brand battery.

 

^Oddly enough, I got the message "Replace battery in Key Remote Soon" yesterday. Was it easy to change the battery?

 

Very easy. Remove the actual key, use a penny or a dime (or the end of the key) in the little groove to pop the back off the fob, then just sub the battery out. Just make sure to seat the new battery in against the positive contacts before pushing it in. Hardest part is snapping the two case halves back together.

And use a name-brand.

 

^Thanks. I'll keep an eye on it and see if this message goes away before changing the battery.