Mini Countryman Diesel Engine Problem Solved

Sounds a lot like what happened with my Mini, I have a Cooper Diesel. Check engine light, rough running, and even some smoke. Have you noticed any hissing sounds when you accelerate? For me, it turned out to be the EGR valve. These are notorious for causing issues, especially affecting emissions test results. It’s all part of the exhaust gas recirculation system, and when it fails, it can cause a vacuum leak and all sorts of problems, especially in diesel engines. Do you know if yours has ever been replaced?

Interesting. Yes, I've also noticed a hissing sound when accelerating, now that you mention it. Given the symptoms I described, do you think the EGR valve is the most likely cause? I'm trying to understand how the recirculation system affects engine performance.

Yep, those hissing sounds pretty much confirm it in my book. Given all the symptoms, it really does sound like a defective EGR valve. It's a common issue and can definitely lead to reduced power, rough running, and increased fuel consumption. I would recommend getting it checked out at a workshop. The automotive repair isn't too complicated but access to the valve on the engine can be a little tricky. I ended up paying around 355€ for mine to be replaced.

Took the Countryman to the workshop. You were spot on, EGR valve was indeed the culprit. New one fitted and now it runs like a dream again. Thanks for the help!