Skoda Fabia Oxygen Sensor Error

That sounds like a classic oxygen sensor heater failure. I had a similar issue on my old BMW. The DME was throwing codes related to the air-fuel ratio being off. Have you checked the wiring and the plug connection to the oxygen sensor itself? A corroded or loose connection can cause this.

Thanks for the tip! I'm not super familiar with car components. Where exactly is the oxygen sensor located, and is it something I can easily check myself without special tools?

Yes, a defective connection is a common cause. The heater element needs a good connection to function. If you're not comfortable doing electrical diagnostics, I'd suggest taking it to a workshop. They can properly test the sensor and wiring harness.

Took the Fabia to the shop. It was a faulty connection on the oxygen sensor heater element, as suspected. 95€ later and the malfunction indicator is off. Thanks for the help!