My F7 had the check engine light come on twice during a 4 day ride. The oil pump was adjusted before the ride and I even ran about 8-12 oz of oil at night as the temps were always near -20 to -40f. The first time the light flashed, I let the sled sit a few minutes, but the light would keep flashing at anything over 4000 RPM. It quit when I pinned the throttle a few times. You could then feel the water start circulating through the running boards again. Ran fine the rest of the day. Mornings were always a problem. The sled would keep bogging and not circulate water until the the radiator cap was cracked open. You could then feel the water begin to circulate through the exchangers. I did run the sled in the ethanol position when the temps dropped below zero. The one night that I forgot, the check engine light came on after a prolonged pace of 35-40 MPH at about 5500-6200 RPM. Again, after I cracked the cap and pinned it a couple times again, the water would start circulating again. Its not an oil issue or air issue on mine, it has over 1400 miles on it now. Would a slight overfill of coolant not allow enough room for expansion and be causing these problems? The sled would run perfect when pushed hard and the RPMs were above the 5500 range. It was just the mornings and prolonged cruising that caused problems. Otherwise, the sled was perfect for our 825 mile trip. Best sled I have ever owned. :wub: Thanks, Bill.