Mini Cooper check engine light air valve issue

That sounds mighty familiar! I had a similar check engine light saga with my Cooper some time ago. Have you checked the vacuum hoses around the throttle body and intake manifold? A vacuum leak there can cause all sorts of havoc with the manifold pressure and trigger that pesky light. It's often a simple fix, like a cracked or loose hose. Give those a good once over before you start chasing more complex gremlins!

When you experienced the issue, were there any noticeable changes in engine performance, such as rough idling or diminished throttle response? Furthermore, was the location of the vacuum leak readily apparent upon visual inspection, or did you require specialized diagnostic tools to pinpoint the source?

Absolutely, the engine was definitely running rough, especially at idle. It was a bit like it was struggling to breathe. And to answer your second question, no, it wasn't immediately obvious. I tried the visual inspection route first, but ended up taking it to a workshop. They smoked it out and found a tiny crack in one of the vacuum hoses near the throttle body. Honestly, given the labor involved, sometimes it's just easier to let a professional handle it, unless you're really confident with your wrenching skills.

I appreciate you taking the time to share your experience. It seems that a defective hose connection from the pump to the valve was the source of the problem. I ended up getting it sorted out at a workshop; the replacement of the vacuum hoses and associated labor came to 175€. Hopefully, this information will be helpful to others in the future.