What is a thermistor?

Unlike a thermostat, a thermistor does not switch anything — it simply reports temperature to the control board as a resistance value. An oven sensor typically reads around 1,080 ohms at room temperature; one reading well high makes the board think the oven is cooler than it is, so it overshoots and burns everything. Because they can drift rather than fail outright, test them across a temperature range rather than at one point, and check the harness for intermittent breaks.