Seat Mii Coolant Loss and Check Engine Light

Low coolant and a check engine light is never good! I had something similar happen with my Mii. Have you checked the radiator cap? A faulty one can cause pressure loss, leading to coolant disappearing. Also, look closely at all the radiator hoses for any signs of leaks, even small ones. Sometimes, air pockets can also cause issues, so try bleeding the system if you know how. What about the water pump? Any weird noises coming from that area?

Thanks for the quick reply! Engine overheating is scary. The radiator cap looks okay at first glance, but maybe it's not sealing properly? How did you bleed the system in yours? And regarding the water pump, what kind of weird noises are we talking about? A gurgling sound or something else?

The radiator cap might seem fine, but they can be tricky. As for bleeding, honestly, I didn't do it myself. I took it to a workshop because I was worried about doing it wrong and making things worse. About the water pump noise, it was more of a whining sound that changed with the engine speed. However, if the error memory points to a connection issue, that's probably the place to start. In my case, it turned out to be a corroded connector that was messing with the coolant sensor. Best is to get it checked.

Just wanted to let you know it's fixed! It was a bad connection, like the error memory said. Cost me 95€ at the workshop, but at least the engine overheating worry is gone. Thanks again for sharing your experience; it really helped me get the right diagnosis.