Seat Tarraco Hybrid Key Fob Issue

Sounds like the battery in your key fob is indeed the culprit. Is the car's main battery healthy? Sometimes a weak car battery can cause strange electrical issues, like a phantom drain affecting the key. However, given the error message and keyless entry malfunction, the key fob battery is the prime suspect.

Thanks for the quick reply! The car's main battery seems fine, no issues starting or anything. But is there any chance it could still be something else besides the car key battery?

While a weak car battery could theoretically contribute, it's like trying to blame a leaky faucet for a flood when the main water pipe is burst. The key fob battery is the direct power source for the key's functions. Replacing it is the logical first step and almost certainly the solution. If the problem persists after replacing the battery, you might want to visit a workshop.

Changed the car key battery, and that solved the issue! Cost me 37€. Thanks for your advice!