Key Fob Re-Pairing

[pixelcellar]

I've just come to change the battery on one of my key fobs (I only ever use one) and it now doesn't unlock the vehicle. The 'spare' does but I want to make sure both work.

It's a brand new 2025 battery as required, even tried putting the old one back in which wasn't completely dead (car advised changing though) and still no joy.

Seen a few options around on the internet to 're-pair' the key to the car but none have worked, not sure if they are relevant for my model so could just be old info.

It's a Mk7.5 PP 3 Door Manual GTI fyi.

Any help appreciated so I don't get shafted by the dealers!

[bogwoppit]

Assuming the battery you've changed isn't a dud, have you tried re-syncing the key?

[pixelcellar]

Ok, just tried that, alarm went off, put key in and turned ignition, no joy. The key light doesn't light either, would be odd if both the existing battery (which was still working in the fob till I swopped it) and the new one were now dead, the one I put isn't that old either as I use the same type for heart rate monitors.

Should the key red led light if there is power regardless of if its paired do you know?

[bogwoppit]

Yes, I'm going off memory here, but the fob should light up when you press the button, regardless if it's synchronised or not.
You can see it on these 2 videos, before the key is synchronised:

https://www.youtube.com/watch?v=yJqpajzfuEM&t=143s

https://www.youtube.com/watch?v=lb0UdmAVmz4

[pixelcellar]

Ok, right will try again tomorrow when new batteries arrive as thats got to be the issue then if the red led should light regardless.

[madstaff]

I had this same problem and it was the crappy batteries off ebay, think your getting a bargain buying a strip of 10 - probably fake GP Lithium as half of them were dead when tested.

Just grabbed some from Screwfix, Varta CR2025 twin pack cost about £2-50 IIRC.

[EB2019]

if its possible to mess up, did put the battery in the right way up?

[pixelcellar]

if its possible to mess up, did put the battery in the right way up?

Lol, yeah even my non technical skills figured that out.... Hoping its just the battery though odd both the original and new ones are completely dead...

[joe6]

Had the same problem when changing to a cheap battery. Went dead after about 3 days and showed 0.6v on the multimeter. Worked fine with a new battery without resyncing.

[Vwjap]

2032 fits aswell 😂,