Mini One Diesel Coolant Loss

I had a similar problem with my Mini Cooper a while back. Coolant level was dropping, and the check engine light came on. First thing I'd check are the radiator hoses for any signs of a coolant leak. Also, inspect the radiator cap; a faulty cap can cause pressure loss and lead to coolant loss. Have you checked for any visible leaks around the engine bay?

Thanks for the quick reply! I did a visual inspection of the radiator hoses and the radiator cap, but didn't spot anything obvious like a coolant leak. Could it be something less obvious, like air pockets in the cooling system, or something else entirely that I'm missing? Where exactly did you find the leak in your Mini Cooper?

Turns out the issue was a defective plug connection as well! But honestly, I am not comfortable giving guidance beyond what I already did. It's better to get a professional opinion; that's what I did. They can properly diagnose the issue and prevent further damage.

Just wanted to give you an update. Took the Mini One to a workshop and you were spot on! It was indeed a defective plug connection. They replaced the faulty connector, cleared the error memory, and everything seems to be running smoothly now. The final bill was 95€. Thanks a lot for your help and pointing me in the right direction!