I just purchased a 06 sportsman 500 the first of march and the hot engine came on in about 15 minutes, fan came on when I parked it and continued to run for at least 45 minutes before I unhooked the battery. Called dealer service dept. and they said sounded like a faulty sensor since the radaitor didn't feel hot. Came back out and tryed it again the next day and after about 20 minutes it started spitting out coolant, about a cup and this time no fan. Took in to the dealer and they said the ecm went out. They replaced it and so far after an hour or so of use no more problems. The fan cycles when it gets hot and then goes off when engine cools. Hope this helps. The hot engine light wouldn't go out until the computer was replaced and I couldn't access any hours or miles or anything else for that matter.