Scenic Check Engine Light Rough Idle

Sounds familiar! I had a similar issue with my old Opel Astra, although it was a diesel. Check engine light, rough idling, the whole shebang. Turned out to be a vacuum leak in one of the hoses connected to the throttle body. Could be worth checking all your vacuum hoses for cracks or splits. Any hissing sounds?

Hissing sounds, huh? I haven't specifically listened for that, but I'll definitely give it a shot tomorrow. Which vacuum hoses were affected on your Astra? Was it difficult to spot the leak?

On the Astra, it was a small hose tucked away near the intake manifold, almost impossible to see without getting right in there. Honestly, unless you're super confident, I'd get a mechanic to take a proper look. Vacuum leaks can be tricky to pinpoint, and messing with the throttle body without the right knowledge can cause more problems. Could be the air valve itself, but a pro will know for sure.

Thanks a lot for the advice! I took it to the workshop, and you were spot on – it was indeed a defective hose connection to the air valve, like I initially suspected. New hose and some labor later, and the check engine light is gone! Cost me 175€, but totally worth it.