Seat Altea Key Battery Issue

I had a similar issue with my Seat Leon, although it's an older model. Keyless entry quit, and I got a low voltage warning related to the car key. Often it's something simple, like a dead key battery. Have you checked the battery voltage?

I haven't checked the voltage directly. How did you figure out it was the battery? Did you have to reprogram the car key afterwards?

That's exactly what happened to me. I didn't measure the voltage, but the symptoms were the same. I didn't need to reprogram the car key after changing the battery. If a new key battery doesn't fix it, maybe visit a workshop to check for other problems.

I changed the battery in the car key as you suggested. It cost 37€, but the error is now gone and everything works.