CX-5 still flashes key fob battery low after battery change

[Gooogle]

My key fob was dying so I replaced it with a 2025 battery last week. It works but often when I get into my car, it still says no key detected and I have to press my fob on the started button to start.

Any ideas what is going on? This didn't happen last time I changed the battery. 2019 CX-5

 

[Mazdiod2]

That is pretty weird.
I bought some batteries, I think they were a 4-pack. The first one(s) were ok, but when I tried to use the remaining batteries several years later they were already low.
Did you buy some fresh ones this time? I had to go out and buy another pack.

 

[wlong01]

Buy new batteries.

 

[HyFlyer]

You can also squeeze a 2032 in there.

 

[Cooper1]

Make sure the other fob isn't nearby. My wife's fob will do that when we're both in the car.

 

[wlong01]

Make sure the other fob isn't nearby. My wife's fob will do that when we're both in the car.

That shouldn't happen. We always ride with two fobs in the car and never have a problem.

 

[MrViking]

Do the simple check first. Check the voltage on the new battery.

 

[cxha]

Do the simple check first. Check the voltage on the new battery.

Great advice, there really is a problem with so-called new batteries which are faulty and so many owners have had issues when switching to them and will not accept the fact that they can be bad.

 

[Budgetta]

My key fob was dying so I replaced it with a 2025 battery last week. It works but often when I get into my car, it still says no key detected and I have to press my fob on the started button to start.

Any ideas what is going on? This didn't happen last time I changed the battery. 2019 CX-5

Here is the solution. I just fixed my wife's fob using it.

B

Post in thread 'Key fob low battery on dash but new batteries?'

Feb 25, 2026

Mazda Key Fob Low Battery Issue

It means it has gone into the power saving mode. Usually when the old battery is about to die, the Fob turns on the Power Saving mode itself. So, from there on you need to get the fob so close to the ignition button to start engine + your keyless entry won’t work.
So, after you change your old batteries and put a new battery, the fob will continue to be in the Power Saving Mode. There are simple steps to take the Fob out of Power Saving mode.

1. Turn on the Engine
2. Use your fob and press your “Lock” button 4 times
3. You’ll see the indicator (red...

• Budgetta