Good day,
I use a Skoda Karoq 2023, I have 2 keys with the KESSY system.
The main key I use showed symptoms of a dead battery: a problem with opening the car doors and trunk.
I replaced the battery in the key exactly according to the car's user manual available on the website, i.e. by performing a "reset" (pressing any button on the remote control between removing the used battery and installing a new one). Of course, I used a new battery of the same type that was factory-installed in the key; I also checked it for efficiency.

Unfortunately, after replacing the battery, the key stopped working, i.e. it does not allow you to open the car either by approaching the car door and opening the handle or by pressing the appropriate button on the remote control.

I also performed the key re-synchronization procedure, available in the "Keys, locks and alarm/Key/Troubleshooting/Key not synchronized" section of the manual; unfortunately, it also failed - I still can't open the car with the key 😞
I will also add that the second (reserve) key is working without any problems for now. However, I am afraid that the battery in it may soon die as well and I will be left without the possibility of unlocking the car.
Is there a solution to this problem?

Does the little red light in the key light up when you press the buttons?

 

If not, have a look at the battery you fitted in the key, some of them have a clear plastic sticker that needs to be removed.

I've never done the "reset" step - I just change the battery,

 

Not had any issues with Karoq key with CR2032 battery, but only changed it once.   Our 2018 SEAT Ateca uses CR2025 and they seem very sensitive - some batteries work and some don't.  Even one the dealer changed only lasted a month.

Of course, I checked the appearance (flashing) of the "red light" in the key after pressing any button - it is identical to the spare (much less frequently used) key (which works normally)...
Thanks to the procedure in the instructions "pairing the key" I manage to "pair" the key with the car to such an extent that I can get into it and start it, but only after removing the lock cover and pulling the key blade out of the remote control housing - I have to open the door with the key blade. I can't imagine driving without this lock cover or putting it on and taking it off every time I get in and out of the car. It makes no sense, the car is only 1 year old!
For now, I'm going to an authorized service center to fix this issue, but I'm afraid that they will simply program this non-working key via the computer (via the manufacturer's software that gives access to the computer).

What next, when the warranty ends? Drive many kilometers and pay an authorized service center for something as trivial as replacing the battery in the key???

Edited 30 July, 20241 yr by langolier

Do you have to hold the key near the start button for the car to start?   If yes, then you haven't paired the key - it will always start if the key is held in the correct place, even without a battery in the key.

 

I suspect the pairing hasn't worked properly - I don't know the procedure because I've never had to do it but it is often the case that this type of thing takes several attempts.

 

Normally, you just change the battery and the key works.

Hello langolier,

I exactly have same issue with Karoq 2023 with kessy. So after 2 years. Same procedure applied as indicated in the book withe new varta battery, the day after I got the message asking to change the battery. same stupid problem. I have contacted the garrage, to resynchronise 80€. I have a 5 years waranty, they don't accept to do it under warranty!!!! wearing part ??? Bad will... Last time that I buy skoda!

Dishonest!

How did you manage your problem?

Thanks

I have changed the batteries in the key fob probably 4 times over 6 years and like Rory have never had any problems they worked straight away without pairing

Edited 16 October, 202516 Oct by Karock

Thanks for reply, I'm happy to know that it should be possible....

Could you check my step, if I did something wrong compared to you?

So Karoq Aug-2023 with kessy

• got message on console please change key battery

• 2 days after I bough a CR2032 varta new battery

• Karoq, engine and contact off, all door closed but not locked

• Second key away

• I'm close to the car.... Should I go away?

• Open the key, remove the battery, install the new one, close the key, press button to lock or unlock the doors--> no action, touch the door handle, nothing (LED on the key will go on if I press a button or touch the door handle, so battery and communication key and kessy system should be OK.

• Retry the same operation, but push a key button after removing the battery, reinstall, --> same problem

  ???

After I try that procedure to resynchronize but it is just "Bull****":

• Press any button on the key

• Unlock the door within 1 minute with the key via the locking cylinder

Edited 17 October, 202517 Oct by barbichon
Forgot something

I simply removed the original battery in the car and replacedwith the new.

Shut the doors and tried to reopen outside, never had a problem. My car is 2018 so the software could be different on yours.

1 hour ago, barbichon said:

Could you check my step, if I did something wrong

Typically with VAG keys you need to press a button on the remote after removing the old battery & before installing the new one. Worth a try.

Edited 17 October, 202517 Oct by Rbz5416

I also did it like that

1 hour ago, barbichon said:

I also did it like that

Assuming you replaced like for like, some keys have 2025 & some 2032, then I'd try another new battery from another source. I used Panasonic batteries from Amazon on my Polo.

I believe the non-Kessy keys use CR2025 and the Kessy ones CR2032.

I replaced batteries in both of the Kessy keys on my previous MY2021 Karoq. Used Panasonic batteries bought on Amazon. Both times just removed old battery & replaced with new one, worked fine. Only difficulty is getting the fob open in the first place!. Haven't had to replace any on current car yet (that's tempting fate!) , which reminds me, need to put spare battery in wallet!

Thanks for reply....

I have faced the same problem. I replaced the key battery with the same type and even tried other batteries, yet the car’s engine works while the doors do not open, despite all the known key re-synchronization procedures, which failed.

I went to a car electrician, but he couldn’t find a solution. When he consulted his contacts in the field, he was told that this issue is common in KAROQ models, and resolving it requires the intervention of a special engineer working for the company to reprogram the key.

How can a company commit such a serious and absurd negligence?!
How is it acceptable that a car owner should be forced to send their vehicle from Algeria to the nearest dealer in another continent (Europe) just to replace a key battery?
This is completely unacceptable and reflects a blatant disregard for customer convenience and rights!

If there is any available solution, please let me know. Thank you

Apologies if I've got the order of streps taken wrong but here goes

I got the low battery warning on the dash
Changed the battery (admittedly a cheapo £ shop CR2032)
Nothing/nowt/nada/...
Removed and tested the voltage. Was Ok

Re-inserted the same battery

Nothing/nowt/nada/...

Didn't try to re-pair/synchronise

Inserted a different Duracell CR2032
Worked straight away

Ok, the italicised bit. Is there a possibility that the battery fitted had enough oomph in it to corrupt the pairing procedure but not enough for it to do what you wanted in the first place? Or going through the pairing procedure effectively meant the key was never going to work even with a different battery?

Based on my experience it took a third try of fitting a new fully charged battery before the fob worked. Varta should be good but ......

My daughter ended up with a "not working" non KESSY key when she replaced the Panasonic CR2025 with another Panasonic CR2025, last month, in her 2019 SEAT Leon Cupra, she had had the "low battery" warning for a week or so, so just replaced the battery, to get out of that issue, she refitted the previous battery and the key worked okay.

I swopped the battery for the new one that she had previously fitted to this key and found that the duration of the flash of the key's LED was shorter than with the older battery, I removed>fitted>pressed a button a few times and at least one time, the LED "flash" looked okay, the out of circuit voltage for the old battery was 2.99V and the new but not working every time battery out of circuit voltage was 3.31V.

Having lost trust of this new Panasonic CR2025 battery, I grabbed another Panasonic CR2025 which was from her same "multi buy" of Panasonic CR2025 batteries, and it worked okay, so a few days later I replaced the Panasonic CR2025 in her other key with the last of that "multi buy" card of Panasonic CR2025 batteries - seeing as I had checked that 2nd key's battery out of circuit voltage which was 3.00V, and it worked okay as well.

So in her case, it would appear to just have been a faulty Panasonic CR2025 which got disposed of along with the previous 2 keys Panasonic CR2025 (used) batteries - just one of these things, or she was just unlucky, so I do now know that it can happen even when buying Panasonic key batteries.

Measuring the open circuit voltage of a battery alone can be misleading you need to measure its current capability under load. A quick test is to momentarily measure the current on the amps range (very momentarily) you should then be able to find the decent batteries.

On 04/01/2026 at 21:14, Karock said:

Measuring the open circuit voltage of a battery alone can be misleading you need to measure its current capability under load. A quick test is to momentarily measure the current on the amps range (very momentarily) you should then be able to find the decent batteries.

Use the meters 10 Amp scale when doing this - usually requires plugging positive test lead into dedicated meter port.

On 04/01/2026 at 21:14, Karock said:

Measuring the open circuit voltage of a battery alone can be misleading you need to measure its current capability under load. A quick test is to momentarily measure the current on the amps range (very momentarily) you should then be able to find the decent batteries.

Fair enough comment, but I was not going to continue using that "iffy" new CR2025 so was using checking its out of circuit voltage as a "starter for 10" check, checking the open circuit voltage of an "in use" used battery does quickly let you know if a still working battery is good to re-use/re-fit as I had idea how long the second key's battery had been in use and checking its present out of circuit voltage allowed me to bin it also and fit another new CR2025 to that second key.

I do know that a battery's internal resistance will limit its ability to supply current to its load by the way.

The earlier kessy fob that use CR2025 take more current when being operated than a CR2025 is specified for.

I've found Energiser batteries always worked, whereas it was random with other brands, even Duracell.