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Key fob battery low warning.


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Had my 2019 Fiesta ST-Line 140 from new in October 2019, Just clocked up 20,000 miles this morning.

Started car up to come home from work and it showed up an error message on the dash saying " Key Fob battery low, replace battery soon"

I've never had a battery on a key fob run out on me before, and I certainly wouldn't expect it a car only 16 Months old.

Got the spare key out when I got home, which has never been used and that also gives the same error message.

So it's either a bug of some sort, both batteries have run low at exactly the same time (seems unlikely) or there is some built in obsolescence which falsely prompts you to replace the batteries. 

Anyone seen this before, and is there any way of resetting the error message?

I haven't checked the user manual yet but I'm assuming you can still start the car with a key if the battery does die?

 

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Well it may be that simple but since my previous car ran 3 years without a battery replacement and the car before that over 10 years I'd be surprised they would have run out by now. And to get both to run out on exactly the same day seems a bit unlikely.

I don't want the hassle of working out what batteries I need, how to fit them without destroying the key fob and spending £10 + delivery on something that might not be necessary.

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Even if the key fobs are not used they are still constantly giving off a signal.   If they were both renewed at the same time then they would probably start to go flat at the same time.   As Pete says, it a simple job and, if you're not sure, there are plenty of guides on Youtube.

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The reason I was concerned on doing it myself was due to the experience I had with my old Citroen. The battery lasted 10 years but when it finally went I decided to do it myself as it looked pretty easy.

Inserted a flat bladed screwdriver and twisted carefully to prise the cover open and the circuit board inside just fell out along with a metal clip that held the battery in place.

Couldn't get it to go back together again and Citroen quoted me well over £150 to get another one. Might just have been shoddy Citroen quality but I didn't want to repeat that experience with this one.

I realise batteries have a shelf life even when not used but they must be using pretty cheap and nasty ones now if they are flat after 16 months. All of those type of batteries are sold with a minimum 5 year lifespan in my experience.

 

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I had the same thing happen to me. Replaced both batteries in both fobs all sorted.

That was the first thing to go, then I needed a tyre, then MOT, then brake pads.

However the car has not cost me a lot in the last 3 years so I could expect wear and tear items to start going and needing to be replaced.

My car is 6.5 years old and brilliant so no complaints.

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Just remembered I had a pack of those batteries I bought for some PC bios replacements.

Pack is dated to July 2025.

Just watched a you tube video and put one in.

Still giving the same  error unfortunately 

16116998931758479066116549930432.jpg

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My dash started showing the error, had it for a few months before I got around to getting the spare key which also showed the same message.

Incredibly easy to replace the battery though and they're only a couple of quid, just make sure you get the right battery (CR2032)

 

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7 hours ago, Blatto said:

Had my 2019 Fiesta ST-Line 140 from new in October 2019, Just clocked up 20,000 miles this morning.

Started car up to come home from work and it showed up an error message on the dash saying " Key Fob battery low, replace battery soon"

I've never had a battery on a key fob run out on me before, and I certainly wouldn't expect it a car only 16 Months old.

Got the spare key out when I got home, which has never been used and that also gives the same error message.

So it's either a bug of some sort, both batteries have run low at exactly the same time (seems unlikely) or there is some built in obsolescence which falsely prompts you to replace the batteries. 

Anyone seen this before, and is there any way of resetting the error message?

I haven't checked the user manual yet but I'm assuming you can still start the car with a key if the battery does die?

 

The batteries in car keys for cars with keyless ignition tend to not last long, I have to replace the battery in my mum's nissan micra k12 key every 14 months (yes a car from 2003 has keyless ignition)

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25 minutes ago, aguycalledmal01 said:

I have tried Duracell in the past with the same result. I now use Panasonic cr2032 . If you search the web you will see many posts about this and some button cells are not as good as others.

if the make of battery actually makes a difference (strange if so) I have Energizer in mine and another Kuga which worked perfectly....although OP has used that so its a strange one...

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Mine flashed up the day before a service, so had it changed then. Unless previous owner changed it, it lasted about 2 1/2 years. Was charged over £8! 😮 Lost count how many times I've changed on my Mother's Fabia. Both cars have keyless start. I don't think I ever changed the one in previous car (mk1 Fabia) in 13 years of ownership and bought it 2 year old.

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Might be the keyless ignition that's making them last less time I suppose.

Put my new  Energizer batteries dated as OK until July 2025 into my main key and the backup key and opened the car and then started it, I'm still getting the error with both fobs with the new batteries. 

The original was a Panasonic battery. Found a pack of 2 Duracells on my Weekly shop at the supermarket on the way home tonight so will try those in the morning just in case my energiser ones aren't working. Incidently they are dated as OK until September 2030.

 

 

 

 

 

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I put the new duracells in this morning but was still getting the same battery low warning.

Did a bit more searching online at lunchtime and found a suggestion of unlocking and locking the doors 3 times with the key fob.

As unlikely as it sounds, that seems to have fixed the fault 🙂

 

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3 minutes ago, Blatto said:

I put the new duracells in this morning but was still getting the same battery low warning.

Did a bit more searching online at lunchtime and found a suggestion of unlocking and locking the doors 3 times with the key fob.

As unlikely as it sounds, that seems to have fixed the fault 🙂

 

Good to hear! A bit like how to reset the one touch window up/down if it ever stops working js to pretty much just put the window up and down about 4 times 🤣

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Yeah would be good if they put a list of these fixes in the manual 🙂

I put the original panasonic battery back in the spare key and that works fine now also.

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26 minutes ago, Blatto said:

I put the new duracells in this morning but was still getting the same battery low warning.

Did a bit more searching online at lunchtime and found a suggestion of unlocking and locking the doors 3 times with the key fob.

As unlikely as it sounds, that seems to have fixed the fault 🙂

 

Yes it needs to communicate with the car.

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21 hours ago, FezMan said:

Good to hear! A bit like how to reset the one touch window up/down if it ever stops working js to pretty much just put the window up and down about 4 times 🤣

well with that its just making the car relearn the up and down limit of the window

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23 hours ago, Blatto said:

I put the new duracells in this morning but was still getting the same battery low warning.

Did a bit more searching online at lunchtime and found a suggestion of unlocking and locking the doors 3 times with the key fob.

As unlikely as it sounds, that seems to have fixed the fault 🙂

 

So I actually got my car back from the garage today after it having a new battery put in due to the old one being confirmed as faulty

First thing I saw when I got in? Key battery low (wasn't when it went into the garage) Got home and did the lock/unlock 3 time thing and low and behold my key battery is now fully charged 😅

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