Why does my SC-200 overheat over 171°C regardless of temperature?

It is possible that the 40-A-Solid-State-Relay, which controls the power supply of the main element, is blocked in the closed position. This system is controlled by a 5V DC from the digital controller to terminals # 3 and # 4 of the relay. This 5-volt current closes the circuit between terminals # 1 and # 2 so that power can flow to the main heater. When the smoker warms up near the temperature setting, the controller starts sending the 5 volts to the relay. This also pulses current through # 1 and # 2 to the element, allowing the smoker to maintain a more consistent cooking temperature. If the relay fails in the closed position, the current cannot be interrupted to the element, causing it to continue to heat until the Hi-Limit opens at approximately 340 degrees and the coil voltage to the contactor is cut off. This opens the circuit to the heating element until the smoker cools.