My MES40 is about 3.5 years old and for my last smoke, the smoke chamber temperature went wonky. The push-button control panel stopped working right a couple of months ago - I could only use the minus button to lower the smoke chamber temp and the cook time - but it seemed to be fine using blue-tooth. For my last smoke - When I set the temp to 275F, the chamber made it to 220F +/-. When I set it to 225F, the chamber was closer to 190F +/-. I just received a new control panel from Masterbuilt...lets hope that works. BTW - they did not charge me for the control panel so I am thinking this must be an existing problem that was pretty wide spread.