Worked perfectly when I unlocked the car, but when I parked up and pressed the button, it didn't want to know. My other key works fine, but this key won't unlock or lock the car unless I put the key in the lock now.

Is it the battery? Or something else? Anyway I can reset it if it's not the battery and if it is how much am I looking at?

The car is 4 years old now with 42,500 miles.

Thanks

Does sound like the key - can you switch the one out of the working keyfob to check? Failing that, it may be that the needs re-coding to the car, but I can't think what would trigger that as it was working before. Does the non-working key start the engine with it?

Chris

How do I change the batteries over? Is it numpty-proof? And yes, just checked, the car starts on both fobs.

http://www.seatcupra.net/guide_keybattery.htm

No idea if it's numptie proof lol!

Chris

I've just figured it out as well. Its easy enough. Not sure if this wants to be logged anywhere, but the battery needed is a CR2032 3 volts Lithium. Looks like a large watch battery, or a penny. They seem to made by Sony as well.

It's a dead battery. Its odd the way it just went and didn't die slowly.

Any of those batteries will do, I asked the dealer , he quoted around