Seat Mii Check Engine Light and Stalling

Sounds familiar! I had similar issues with my Mii. The check engine light was on, and the engine stalled sometimes at idle. Have you checked the tank ventilation system? It's a common problem. The pressure sensor might also be involved.

Interesting! When you say tank ventilation, are we talking charcoal canister area? Any specific hoses or components I should eyeball first?

Yeah, charcoal canister is the area to focus on. I'd suggest getting a smoke test done, or you could try to trace the hoses yourself to check for clogs, but it's a pain. Honestly, I ended up just taking mine to a workshop. Saved me a lot of headaches in the long run.

Yep, it was the tank ventilation valve. The hoses were pretty choked up. Got it sorted for 175€. Thanks for the heads-up!