Key fob works on doors, not ignition "low Battery"
 

Hi, I just purchased a used 2020 CX-5 Grand Touring, and one of the two key fobs is either unrecognized by the ignition or else the dash displays "Low Battery," although I put in a fresh battery, twice, to be sure. That key fob operates the doors, hatch, and panic alarm normally and from some distance. Is there something I can do, or what might a new fob + programming cost? are their better or cheaper alternatives to buying a new fob from a Mazda dealer? Any suggestions welcome, and thanks!

If it is a 2020 with low mileage, it may be still be under warranty. Worth checking out. My understanding is the warranty is transferable

My wife has the habit of leaving the fob in her purse and placing her purse in the back seats. She gets the low battery warning when she does this. I'm guessing all the metal in the seats attenuates the signal.

As someone else said- go back to the dealer with it. I would be surprised if a '20 was over 36k so your key is under the original factory warranty.

Thanks! You're right. It was still under the factory warranty, which is transferred automatically with ownership. They identified the problem.

Thanks, everyone, for your help. So the Mazda dealer's service writer told me that my key fob was in some sort of "battery saver" mode that is not mentioned in the owner's manual. They fixed it, and handed me a printout of instructions to fix it myself if it happens again, that I stuck into my owner's manual. But I haven't read it. The other problem of parasitic drain on the battery was due to my ScanGauge II being plugged into the OBD II port. It doesn't draw anywhere near enough current to drain a car battery over months, much less overnight. But apparently it does sometimes cause Mazdas,specifically, to create some other load internally that drains the battery fully overnight. The fix was simple, though. The cord disconnects from either end, so I just pull the cord slightly out of the meter to prevent that from happening. Nonetheless, I'll never have another car without having a ScanGauge II in it. They are just so incredibly useful in so many ways. So it's still in my Mazda, although I have to remember to unplug it when parked overnight.