KitchenAid Microwave Error Code F3

The F3 error code on a KitchenAid microwave indicates the control board has detected a fault with the temperature sensor circuit. Specifically, the sub-code E0 means the sensor circuit has opened (no continuity), while E1 means the sensor circuit has shorted. The control board monitors the sensor's resistance continuously during operation, and when the resistance falls outside the expected range for a functioning thermistor, it triggers F3 and halts operation to prevent overheating or thermal runaway.

For homeowners, the temperature sensor is a small component that monitors heat levels inside the microwave cavity. It tells the control board how hot the interior is so cooking power can be adjusted accurately. When this sensor fails or loses its electrical connection, the microwave has no reliable way to monitor temperature, so it shuts down and displays F3 rather than risk overheating your food or the appliance itself. The sensor itself is a thermistor, meaning its electrical resistance changes predictably with temperature. At 70 degrees Fahrenheit, a healthy sensor reads approximately 1080 ohms, increasing by about 2 ohms for each degree of temperature rise. A reading far outside this range confirms the sensor has failed and needs replacement.