Dead Key Fob

Pitter

Pitter
Contributor
:
2020 CX-5 Signature Azul Metalico
The key fob I have used since the car was new in August of 2019 seems to be dead. This morning I clicked it ten times and nothing happened. I went back to the house and got the spare and all was honky dory. I hope to heaven this is just a keyfob battery issue. How do you change the battery in the keyfob and with what battery? If it is the battery then how weird!. All the literature says change battery after a year. This problem occurred at only six months.
 
Check the manual. It is real easy. Look at the battery to see battery number. You can test FOB by installing battery from working FOB. I suspect it is the battery.

 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
The key fob I have used since the car was new in August of 2019 seems to be dead. This morning I clicked it ten times and nothing happened. I went back to the house and got the spare and all was honky dory. I hope to heaven this is just a keyfob battery issue. How do you change the battery in the keyfob and with what battery? If it is the battery then how weird!. All the literature says change battery after a year. This problem occurred at only six months.
The key fob battery is 2025 coin battery. You can just swap a good 2025 from your spare key fob like CX_FIVER suggested making sure the problem is the battery. The key fob battery replacement instruction is in your owner’s manual.
 
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Pitter

Pitter
Contributor
:
2020 CX-5 Signature Azul Metalico
I didn't find it in the manual (In Spanish) but I'm sure it's there as you say. But anyway thanks a bunch for the "how to" link. Great!
 

brillo54

Resident Curmudgeon
Contributor
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NE Indiana
:
'16 CX-5 GT FWD
For 2016 at least, the battery is a CR 2025.
 
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CX5 GT
Battery is cr2025 actually.
They last about 1 year more or less. Its written in the manual that the lifespan of the battery is low on those fobs.

Mine started dying recently, the car actually gave notice for low fob batyery upon shutdown. I went and got energizer lithium cr2025.
 
:
Ottawa, Ontario
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17 Mazda 6 GT
The fob is "on" all the time, using power even in standby.
Also, if you use the same fob all the time, then that one will more than likely die first.
It's also hard to say how long the battery was actually in the fob. Depends on when the vehicle was built, etc. Could be older than Aug 2019.
Could also be that Mazda uses cheap batteries, or that they had them lying around in a bin for a while before being used in your fob.
Lots of reasons why it's prematurely dead.
Keep us posted.
 
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CX5 GT
Btw fob is not on all the time, it energizes when near the car :)
I tested it with radio and em tester.
But you are right who knows how old are the oem panasonic batteries and if only 1 fob is used it would die sooner.
They are smart fobs as well, if ones uses the door handle unlock, remote walkaway lock and trunk only opening by trunk's button without unlocking car by fob, that also probably contributes to faster battery degradation.
 
I wonder if anyone switches FOBS periodically? I think I am going to change battery in the FOB I an using so it is fresh. Put it away and use the spare. After 6 months replace the battery and switch FOBS. Batteries are cheap and will always have a good spare.
 
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2018 AWD GT Premium Red/Black
I wonder if anyone switches FOBS periodically? I think I am going to change battery in the FOB I an using so it is fresh. Put it away and use the spare. After 6 months replace the battery and switch FOBS. Batteries are cheap and will always have a good spare.
When my battery got low, I bought 2 new ones from Amazon and switched out both the one I use and the spare.

Well actually, I discovered the spare was missing and started a whole other process before it was found, but then I put a new battery in it, and attached a tile tracker.
 

Avoidin Deer

Zoom Zoom, baby
Contributor
:
Central Virginia
:
2019 CX-5 Reserve
I wonder if anyone switches FOBS periodically? I think I am going to change battery in the FOB I an using so it is fresh. Put it away and use the spare. After 6 months replace the battery and switch FOBS. Batteries are cheap and will always have a good spare.
My salesguy told me to swap fobs every once in a while. He didn't mention battery life as the reason...he said something goofy about my car failing to recognize one if it went too longe without being used.

I think someone else told him that alternating fobs was a good idea and didn't explain why, so he made up his own reason.
 

sm1ke

Work In Progress..
Moderator
Contributor
:
Canada
:
'18 CX-9 Signature
My wife carries the second fob. The battery in my fob lasted maybe 8-9 months. I keep an extra battery in the armrest console and a few at home just in case.

If I had a spare, I would store it without the battery installed. Not sure how much of a difference that would make, if any. At the very least it would prevent a hacker/thief from hijacking the fob signal from outside the house, since the fob can't transmit a signal without any power.
 

Avoidin Deer

Zoom Zoom, baby
Contributor
:
Central Virginia
:
2019 CX-5 Reserve
Since no one has mentioned it in this specific thread...

There are folks here who state that they have used a CR2032 in place of the CR2025 because it is a stronger (longer-lasting) battery. I've not tried this. The two are not the same thickness and I've not opened my fob to see what kind of room is in there:

>CR2025 = Diameter: 20 mm. Thickness: 2.5 mm. Capacity: 3v/160 mAh
>CR2032 = Diameter: 20 mm. Thickness: 3.2 mm. Capacity: 3v/220 mAh

Can anyone confirm that the CR2032 fits?
 
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GA prior 16 CX5 GT
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20 CX5 GT + Prem
Btw fob is not on all the time, it energizes when near the car :)
I tested it with radio and em tester.
But you are right who knows how old are the oem panasonic batteries and if only 1 fob is used it would die sooner.
They are smart fobs as well, if ones uses the door handle unlock, remote walkaway lock and trunk only opening by trunk's button without unlocking car by fob, that also probably contributes to faster battery degradation.
How does it know to activate near the car if there is no live circuit active using battery power in the fob to determine that it is near the car?
 
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2014 & 2019 CX-5 Touring(s)
How does it know to activate near the car if there is no live circuit active using battery power in the fob to determine that it is near the car?
Hah! I was JUST going to say this!

The fob may not be transmitting all the time, but it certainly needs its receiver turned on to 'see' it's near the car. Of course it could be low-power polling, but still, it IS 'turned on'.
 
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Ottawa, Ontario
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17 Mazda 6 GT
How does it know to activate near the car if there is no live circuit active using battery power in the fob to determine that it is near the car?
You beat me to it. I was thinking the same thing.
There is also a lot of info out there about how vehicles can be stolen right out of your driveway if you leave your fob hanging near the door. They must be active if the bad guys are able to hack them.
That's just a guess, but it makes sense to me that these things must be doing something while not in use.
Thoughts?
 

Pitter

Pitter
Contributor
:
2020 CX-5 Signature Azul Metalico
When my battery got low, I bought 2 new ones from Amazon and switched out both the one I use and the spare.

Well actually, I discovered the spare was missing and started a whole other process before it was found, but then I put a new battery in it, and attached a tile tracker.
 

Pitter

Pitter
Contributor
:
2020 CX-5 Signature Azul Metalico
Well that explains why none of the watch stores I went had a 3025 battery and they all had the 2025.
Maybe my battery was old but it appears to have been used up at six months. I still have to put in a new one to confirm that's the problem. Tomorrow.
 
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