With my 2021 CX-5 GT with about 32,000 miles, I find that am now getting only about one month after changing the key fob battery before I get a low key fob battery warning from the car. Sure enough, when I check the battery it's dropped in just a month from 3.35 volts to 3.05 volts. The battery in each case was a new CR2032 LiCB brand bought new from Amazon in May 2025. This happened in late May (so I replaced the battery June 1). Now, on July 2, I got the same warning so I've replaced it again. The new battery voltage of 3.35 seems about right, but the drop to 3.05 in just a month is not quite right. Until now I've always gotten several months service from each new key fob battery.

For the record, I have not over-used my key fob in either May or June. Typically, I use it no more than once or twice every day.

Just wondering if anyone else is having an issue like this. Or has a clue to what might be happening. I still have a bunch of the Amazon batteries left but if I get another low voltage warning in about 30 days, I'll try a different brand/source for my batteries.

BTW, YouTube has a good short video on how to change the key fob battery at: I've changed the battery enough lately that I barely need that video these days.

Happy Fourth of July to Mazda owners around the world!

Milt Baker, Pompano Beach, FL

 

I find my batteries deplete quite quickly. Tried Amazon. Now trying Duracell. My previous Volvo would last well over a year. I suspect that they are quite different. The Volvo was just a basic key compared to the Mazda which continually ‘talks’ to the car when in a certain proximity.

I used to keep my key in the hall in a faraday pouch. It once drained the car battery. Dealer said it had been connected continually. I then tested the pouch and it does not do the job. I now use a proper faraday box that seems to work fine.

Could this be your problem?

John

 

Make sure the vehicle is always lock when not being used and keep your keys at least 5 mtrs from the car after locking the vehicle.

 

Lately I have found there are more bad batteries today than ever before.
With my first Duracell battery change for my FOB didn't even work.
They claim a 5–10-year shelf storage life but I question that.
I bought a large package of Duracell AAA batteries a month ago with a March 2030 expiration date.
They lasted a week in my TV remote when it said low battery.
I opened the remote case, and the batteries had actually leaked as did the majority in the package when I went to retrieve them, had to dispose of all of them,
I now use Energizer batteries and have replaced my 2020 FOB battery only twice.
As Grim said I always lock my vehicle and store the keys more than 5 meters (16.4 feet) from it.

 

I thought you might have nailed it, John. What you said about it being "connected continually" made perfect sense--more battery use, so the battery drains faster.

So I took it to the the Mazda help line (800-222-5500) and after being put on hold for a loooooong time my customer service rep to research it, she came back and said definitely NO, the key fob is not connected continually. I challenged her on that and asked her to check further, which she promised to do--and get back to me by email.

Lobstah, thanks for your thoughts on batteries. My key fob battery test good at 3.35 V when I install it, but it drops quickly. What's intersting to me is that this never happened to me before I signed up for the MyMazda app, and that's what makes me think that the MyMazda app

 

I think you have nailed it, John! The idea that the key fob is connected to the car continually and that it ‘talks’ to the car when in a certain proximity seems to fit my experience well. Moreover, I never had this problem before i began using the MyMazda app . . . confirming evidence.

I called the Mazda helpline (800-222-5500) this morning and after being put on hold for a loooooong time, my customer service rep returned to me and said that the key fob is not connected to the car except when I'm using the app, which is almost never. I challenged her on that, pointed out what you said, and she promised to take it up the ladder and get back to me by email.

Lobstah, thanks for your insights. The batteries I'm using at good (3.35V when installed) but they get used up much more quickly. I'm retired and live on the 8th floor of a high-rise, and when I'm at home my key fob is more than 100 yards away from the car, so I don't think it's a proximity issue.

If I hear back from the Mazda helpline, I'll do a post here on what they tell me. Meanwhile, I am thinking that I'll cancel the MyMazda app--it doesn't do much for me other than (apparently) discharge my key fob battery and take $10/month from my bank account!

Milt Baker, Pompano Beach, FL

 

I could well be wrong, but I fail to see how the app can affect the fob battery. Others have said they pay for the app, for me it is free, perhaps that is just for a limited time. As I said, on one occasion I a flat car battery. Car just 18 month old. The Mazda connect technician came to the house and declared the battery as failed, but was able to charge it. Later, the dealer did tests and declared the battery healthy. That is when they blamed the key being too close, (even though it was in a pouch). As said, I now use a faraday box and have not had that problem repeat. My fob batteries now last about 2 months, not great but acceptable.

My wife keeps the spare fob with her. This causes two problems. Seeing two fobs causes the car ‘confusion’, and it reacts in-predictably. Second, the battery drains. I found this trick to stop this happening by putting the fob into sleep mode.


John

 

I keep mine unlocked in the garage and the keys are about 5-6ft away from the car. I don't replace fob batteries more than yearly.

 

So in defense of MAZDA....
everyone is experiencing long wait time when it comes to CSR by phone now not just Mazda. Com 'on dude go look at the sales of new Mazda in just the last 2 years here in the US. How many CSR do you think Mazda hires? lol

I would request if you do get a response from Mazda USA that you post the complete response less your personal information.


My guess is it will not be from the technical engineering department but a customer satisfaction department some auto manufactures call them other playful names making some believe that they are getting a person other than a FACTORY trained auto manufactures mechanic or technician which generally must do the best they can to seek the answers based on how they interpret the information asked or how a customer wrote it. So t many times answers are not technically absolute or completely empirical. In fact, had you researched you would have found the same answer on various verifiable information source that auto manufactures post. These for the MAZDA are TSBs relating to any reported concerns and tested to be a concern or problem from service departments.
__________________________________________________ ______________

As for the Batteries and their life span .. well, that's going to be a tuff one because there is currently NO regulation requirement here in the USA for "FLASHLIGHT" batteries ( intelligent humans all know exactly what I mean) except a more or less voluntary use by or self-life date on the batteries. but not all battery manufactures even do that on all the batteries they manufacture for numerous brand named batteries. There is also very little information about doing any battery testing other than the static voltage of batteries. In other words, unlike a car battery which has CCA and a scan and other numbers that are burned/melted in the case of the battery that gives not only the manufacture date but other important information about that battery.

So what I am saying is don't rule out batteries altogether even if you did just by them and they are a top brand.

My best and advise is to go to Mazda or a shop that you first qualify as doing this type of diagnostics to find the cause of the issue. I say that because what is being talked about is not even normally what a certified and trained Automotive Diagnostic Master Technician would have in the way of professional schooling or training for. So it goes more or less experienced acquired from first having those credentials and hopefully can find the issue in a timely manner of an hour.




ASE

 

What do you drive?