My 2005 MINI Cooper s has been running fine lately and today I refilled the coolant. Could that be why the service engine light lit up? I only pulled it into the garage so I haven't taken it for a Long enough drive to see if it would turn off. I think I noticed that a fan in the engine ran kinda hard when I just started it up, but I'm not sure this is an indication of a problem or not. Help me :(

 

It probably isn't the coolant, but I would go back and make sure you didn't disturb any wires or hoses. A disconnected hose or wire will give the insta-code many times. Getting the code read would take a lot of guess work out of the situation. Sometimes the parts store will read the codes, if not mechanic or the best reader is at the dealer (but not free usually, though you never know)