Hello Dave,
If it's anything like the BMW's it looks like an egr fault
If you have a good honest Skoda dealer they may fess up just like a BMW agent did with me Big problem for BMW but being kept quiet by the manufacturer the parts were also on a long back order and only available to the franchised dealers
The egr valve is made in Korea, so much for German quality
O forgot to say I bolted the BMW back together and BMW eventually fixed it under warranty even though it was out of warranty
Hope this helps,
Ian