Seat Leon Overheating Issue

I drive a Seat Leon too, although I am unsure of the exact year of manufacture. A bypass valve malfunction can certainly cause overheating. Have you noticed any power loss or decrease in fuel efficiency? It is also worth checking the exhaust system for any leaks. What error code is stored in the error memory?

I haven't noticed any exhaust leaks, but I did notice power loss. How did you resolve your bypass valve issue?

In my case, the symptoms were similar, including the loss of power. However, it turned out the bypass valve error was consequential, triggered by a different underlying issue. I recommend you take your Leon to a workshop for diagnosis. It sounds like you may have a similar situation.

Just letting you know it was a false alarm. The bypass valve was fine. The mechanic found another issue that triggered the error. No cost for the bypass valve!