Question about Weber Pulse 2000 with stand

Hi All, I've got this grill and have strange thing: If I keep it on maximum, the temperature goes up, after about 15 min it raises over 300, then it fluctuates ups / down and can reach 350. After that grill shows Error 4 — Er4. So I figured out that it's like overheating protection over 350 degrees. Who own such grill, have you ever met such behavior? I affraid that my temperature sensor may be broken..