First and easiest would be to clean out the radiator fins, I have the 450i model and have had a couple overheat signals and found the radiator fins partially clogged with mud and dirt. I have learned to spray it out after any type of ride in mud or heavy dust. The problem is you cant see in there to see if radiator is clogged !! Found a small spray nozzle with a nice 90 degree bend that I can get in the front to blast water thru the fins. Simple and easy if that is your problem. Good luck!