Hello, I have the same problem, if I run the smoker at 200 inside temp is 170, at 250 inside temp 225, 300 inside temp is 260, at 400 inside temp is 300 and at 450 inside temp is 350. i have been testing this for days, same results. The problem is the RTD, there is no way to reset it like old Traegers, you need a new one, call them and ask them for a new RTD. They wont have any in stock until 04/18/19, when supposedly they will get more in. Mean time I did a little modification, I got a small peace of aluminum foil and wrap the RTD "thermal Couple" the probe inside the grill, a thin layer of aluminum foil. It help me get more accurate temps. At 450 it was running inside at 425, lower temps were on point. I dont want to incentive someone to do this little mod, do it at your own risk if you try to attempt.