Key battery flat

[Cyberman]

My car was built 9 months ago (May '21 build, and I took delivery of it 6 months ago), but it says my key battery needs replacing. I've noticed both keys' light lights up when they get moved or touched, yet according to the manual "The indicator lamp flashes when the button is pressed if all doors and the boot lid are closed."

Can anyone shed some light on this, please?

P.S. Strangely, the manual refers to the key battery as the "button cell", and the sunroof as the "glass roof". The manuals are well written, but apparently by someone who isn't a speaker of English in their day-to-day life, therefore it's hard to know what to search for in the manual's index.

 

[SRGTD]

I’ve read on various forums of a few owners needing to replace their key fob batteries within the first year. Presumably your car has keyless entry? It’s not unusual for they key fob batteries to need replacing at around the 1 year mark on keyless cars. My Polo GTI+ has keyless entry / keyless start and the fob batteries are still going strong nearly 18 months after I took delivery of the car, but I do disable keyless as I consider it to be a pretty pointless feature (that’s just my opinion though). I’m more than capable of pressing a button on the fob to unlock and lock my car.

I seem to remember reading that on the Golf mk8, the keyless function goes to sleep if the key fob after a set period of time ( sorry, don’t know what that set period is) if the fob isn’t moved. It’s a security measure to stop the fob signal being intercepted by signal amplification equipment by any would be perpetrators who are looking to steal a car. If the fob’s asleep and not communicating with the car, it’s not possible for the signal to be intercepted. Once you move a ‘sleeping’ key fob, it’ll start communicating with the car again - the red light on the fob will start flashing as it did in your case - until the predetermined period of inactivity has passed again, when it’ll go back into sleep mode.

On mk8 Golfs with keyless entry, I think it’s possible to permanently disable the keyless entry function via the vehicle settings. If you decide to do this, then your key fob batteries should last longer as your fobs should no longer communicate with the car when not being used. You will need to press the key fob buttons to unlock and lock your car though.

As for the terminology used in the manual - terminology in the English language will differ by country; e.g. USA will refer to a car’s trunk, hood and fenders but in the UK it’s boot, bonnet and wings. In the UK, we refer to the fob batteries as either button or coin cell batteries.

 

[Martinbury]

My car was built 9 months ago (May '21 build, and I took delivery of it 6 months ago), but it says my key battery needs replacing. I've noticed both keys' light lights up when they get moved or touched, yet according to the manual "The indicator lamp flashes when the button is pressed if all doors and the boot lid are closed."

Can anyone shed some light on this, please?

P.S. Strangely, the manual refers to the key battery as the "button cell", and the sunroof as the "glass roof". The manuals are well written, but apparently by someone who isn't a speaker of English in their day-to-day life, therefore it's hard to know what to search for in the manual's index.

My Golf is 10 months now, but I had to replace a key battery a couple of months ago. I have keyless access switched off via the infotainment system and don’t use the car very often. I do use the same key all of the time, leaving the other as a ‘spare’. We also have a Skoda Fabia with keyless start (but not keyless access) and that battery only lasted around 18 months. I guess with all the communication the keys do these days, batteries aren’t going to last as long as previous ones did. As a result, I bought a pack of 6 batteries knowing therefore that I’ll always have a spare. I did find changing the one in the Golf key a little harder, due to having to get a little clip in the right place, but nothing too daunting. Guess it’s just one of the things we need to get used to?

As @SRGTD stated above, when the red light flashes on the key, it is trying to communicate with the car and if successful, the car readies itself for potential use. My supplying dealer advised me of this because I was continually getting 12v battery low messages as well. I used to leave the key in my pocket, but as you can imagine, walking around the house with the car nearby in the garage, the 2 were continually communicating with each other. I now leave the key in a Faraday pouch when not in use and so far () the 12v messages have stopped. Should we have to do such things? Probably not, but if it stops problems, then changing routines is a small price to pay.

 

[Cyberman]

Thanks to both of you for your replies. I find the keyless entry very helpful, especially when carrying things. I often misplace my keys (but usually somewhere in my backpack), so at least I don't have to search for the exact location of the key, and can rest assured the key is somewhere sith me. Now I know I'm not crazy, I'll stock up on the batteries (too bad VW didn't make them rechargeable). I'll be more careful about where I keep the keys, now I realise movement triggers them. Thanks

 

[Cyberman]

I've replaced they battery in the key with a new lithium battery, but the car is still warning me (when I start it up) that the battery needs replacing. Can someone direct me to a setting to reset this error message, please? I can't find anything in the manual.

 

[SRGTD]

I’d try a different battery - there are lots of fake batteries on sale.

Don’t know if it is possible to reset the error message - it should reset itself when a genuine, good quality replacement battery is used.