Seat Toledo Check Engine Light Issue

Sounds familiar. I had a similar issue with my Seat Leon, also a gasoline engine. Check engine light kept popping up. Have you checked for any obvious vacuum leaks? Could be something simple like a cracked hose.

Vacuum leaks, huh? Where should I be looking exactly? Is there a particular area that's prone to problems? I'm not really a mechanic...

Well, in my case, it was a small hose connected to the air valve system. I'd start by inspecting all the vacuum hoses around the intake manifold. A vacuum leak can mess with the manifold pressure and cause all sorts of idle problems and trigger the check engine light. If you're not comfortable doing it yourself, I'd advise taking it to a workshop.

Took it to a workshop as suggested. It was a defective hose connection from the pump to the air valve, just like you mentioned. Cost me about 175€ to get it sorted. Thanks for the help!