Do keys lose programming when the battery dies?

Zaphan58

Zaphan58

Zaphan58

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Hi all, quick question. I have a Golf 8, 1 key works fine and the spare has been sat in a drawer for a 2 - 3 years and does not work. I have put a fresh battery in it, tried putting the working battery from the main key in and also tried as the manual says and putting the fob in the cup holder (where the key antenna is). Nothing has worked, the light on the fob flashes but it will not lock, unlock or start the car.

VW say the key may need re-programming at a cost of £100. What I don't understand is how a key can lose its programming. I get that the battery was flat but surely the programming is not lost if the battery goes flat? Or does it?
 
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Just tried my spare key, it’s been sat in a drawer for 5 and a half years since I bought the car new. Still works and unlocks and locks the doors.
 
Zaphan58 said:
Hi all, quick question. I have a Golf 8, 1 key works fine and the spare has been sat in a draw for a 2 - 3 years and does not work. I have put a fresh battery in it, tried putting the working battery from the main key in and also tried as the manual says and putting the fob in the cup holder (where the key antenna is). Nothing has worked, the light on the fob flashes but it will not lock, unlock or start the car.

VW say the key may need re-programming at a cost of £100. What I don't understand is how a key can lose its programming. I get that the battery was flat but surely the programming is not lost if the battery goes flat? Or does it?
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Programming is saved in an eeprom within the fob, eeproms do not need battery to maintain data so in theory it should never lose its programming.
 
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I suspect more modern stuff would be ok.

We were recently away and the battery in our food scales died, could not buy any batteries that size and they are important for our kids meals, I knew my focus fob had the same battery so put it in. After being back from holiday put new battery in and was fine.

My old Rover however once it was flat, needed re-syncing to the car once, though if I recall I could do this myself.
 
shifty_uk said:
The keys programming has no correlation to the battery.

That doesn’t explain why it’s still not working though.
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New cars are made so poorly, it wouldn't surprise me if one of the modules in his car wasn't updated to fix a bug. I've a friend who works in automotive industry, I'm not going to go into details, but he regularly has to fly abroad to supervise engineers and fix their f ups. Once there was a situation when they had to reflash 100's of cars to fix a very obvious bug.

Cost cuts, offshoring, tight deadlines, redundancies and poor hardware doesn't help the situation. I use to laugh when people said that car industry is run by accountants, but now I'm starting to see what they meant...
 
Manbatius said:
I suspect more modern stuff would be ok.

We were recently away and the battery in our food scales died, could not buy any batteries that size and they are important for our kids meals, I knew my focus fob had the same battery so put it in. After being back from holiday put new battery in and was fine.

My old Rover however once it was flat, needed re-syncing to the car once, though if I recall I could do this myself.
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Old rover keys are renound for it... I tried to fix one recently and failed. But i did fix a forum members key when they put it through the washing machine :cry:
 
I let a key completely die. I tried to use they battery from spare key, which worked, still didnt work. Worked finally once I put a quality brand new battery in.
 
MrRockliffe said:
I thought this happened once. Turns out I just put the battery in upside down :P
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This! Or they sometimes have a clear see through plastic bit or a label on the battery you need to remove so it works properly in the holder.

For the key, sometimes if they don't unlock they need resyncing back to the immobiliser. This, on some cars, can be done by opening the door with the key bit, this will set off the alarm usually, then start the car with the key and it will resync back up and work as a normal key again.

Provided the battery is working and the fob isn't broken. :D
 
Zaphan58 said:
Hi all, quick question. I have a Golf 8, 1 key works fine and the spare has been sat in a draw for a 2 - 3 years and does not work. I have put a fresh battery in it, tried putting the working battery from the main key in and also tried as the manual says and putting the fob in the cup holder (where the key antenna is). Nothing has worked, the light on the fob flashes but it will not lock, unlock or start the car.
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Did you ever check or use the spare key fob to know if it ever did work ?
 
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I thought the NFC chip in the key that enables starting the engine did not need any power at all - and is inductively charged by the nearby receiver to be able to generate/transmit it's code.
(used to work for company that built them for cars and farm-animal tagging)
the remote locking is obviously another story and needs power in the key, which is where having a physical door lock/slot for a key is invaluable
 
i thought they need syncing again if pressed too many times when the car doesn't unlock, a feature that minimises someone who finds the key walking around trying all the nearby cars (or make of car on the fob)
Skoda resyinc is opening the car door manually then ................cant remember its in the manual
 
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Manbatius said:
Amazing, I also can't say anything I put my wallet through the wash last week.
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Believe it or not these modern car keys don't like going through washing machines... if I remember rightly it just ate through a load of traces on the board so now it's just a board of jumper wires with a few components on. Was one of these new fangled proximity keys as well :cry:
 
Anyone had the rubber part of car key disintegrate on them? Its happened to both of mine rather than spend what the dealer wanted to charge for a new one I bought a couple rubber pad replacements the originals are glued in but these aren't so to stop them falling out I just wrapped them in black tape not pretty but not really worth shelling out for new keys
 
Vince said:
I think that was @Meatball if i remember rightly... Does that key still work I wonder?
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You are correct. All functions (Keyless entry, remote unlock / lock) all work as normal, no reprogramming needed.

It had been through the washing machine and it was sat in a drawer in pieces for months before I saw the thread and thought I’d ask.
 
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