Both EGT gauges have stopped at the same time on our D120 so I suspect something at the unit end rather than the sensors. Is there anything I can try to fix it without sending the unit away.
Give our tech support team a call at 425-402-0433 to talk about the EGT issue. If you want to surpress the readings while you troubleshoot, there's a toggle under SETUP > SENSORS > EGT
