Mine does it too, and so did my other vx in the Texas heat with ac on in stop and go traffic, I just turn ac off and sweat til I start moving. Funny thing is the temp gauge in the truck says normal or tad over half when scan gauge says 210 , but after it gets just 6 degrees warmer the needle shoots way over, I have let it get to 222, too hot for me, no leaking coolant, coolant new in last yr and half and royalmpurple wetter always used too.