Skoda Superb Diesel Engine Issue

I had similar symptoms on my Superb. Check the crankcase ventilation valve for leaks. Is your fuel consumption higher than usual? It can affect emissions and cause rough idle too.

Thanks for the quick response. Where exactly is the crankcase valve located, and is there an easy way to check for a leak myself before taking it in?

It's usually on top of the engine. I wouldn't advise messing with it yourself unless you are confident. Given the symptoms, particularly the smoke and loss of power, I recommend getting it checked by a professional. It could save you from causing further damage.

The crankcase valve was indeed the problem. I got it replaced, and everything is running smoothly again. It cost me around 360€. Thanks for your input; it helped a lot!