Skoda Octavia Door Lock Problem

Sounds like a faulty door contact signal. Have you checked the wiring harness where it enters the door? Those automatic locks can go haywire with a bad signal. Does the car alarm go off randomly?

Where exactly should I look for the wiring harness? And how do I know if the contact signal is actually defective?

The harness is usually between the door and the car body, protected by a rubber boot. If the contact signal is bad, the car alarm might act strangely. Best bet is to get it diagnosed properly at a workshop.

Took it to the shop and you were right. They found a faulty connection in the door latch. Repair was 95€, thanks for the help.