Skoda Fabia Diesel power loss and hissing noise

I had a similar issue with my Fabia. Reduced power and engine misfire can definitely point to airflow control problems. Have you checked the intake manifold flap control? A defective switch there can cause those exact symptoms.

Interesting. When yours went, did you notice a loud hissing sound when accelerating? And was your fuel consumption higher than normal?

Yes, those were my exact symptoms. The hissing is likely the air leaking past the malfunctioning flap. Higher fuel consumption is also to be expected when the airflow is not properly controlled. I strongly suggest a visit to a workshop for diagnostics.

Thanks for the help. It turns out it was the intake manifold flap control, just like you suspected. Cost me 465€ to get it sorted at a garage, but the Fabia is running smoothly again.