Whirlpool Microwave Error Code F1 — Open Thermistor / Temperature Sensor Fault
What this means
The F1 error code on Whirlpool microwaves indicates the oven cavity thermistor (temperature sensor) has an open circuit or is reading outside the expected range. The thermistor monitors the oven temperature to prevent overheating and to regulate cooking sensors. When this fails, the microwave cannot accurately determine internal temperature and will not operate.
Step-by-step fix
3 stepsReset the microwave
Unplug the microwave for 5 minutes (or turn off the breaker if hardwired over-the-range model). Plug it back in and check if the error clears. A power surge can sometimes cause a temporary sensor reading error.
After plugging back in, wait for the display to fully initialize before pressing any buttons.
Access the thermistor
Unplug the microwave. Remove the outer cabinet cover (screws at the back, sides, and possibly underneath). The thermistor is typically a small bead or capsule mounted inside the oven cavity wall, with two thin wires leading to the control board.
SAFETY WARNING: Microwaves contain a high-voltage capacitor that can hold a lethal charge even when unplugged. Do not touch the capacitor or its terminals. If you are not experienced with microwave repair, stop here and call a professional.
Test the thermistor
Disconnect the thermistor wires from the control board connector. Test resistance with a multimeter — at room temperature, most microwave thermistors read approximately 50,000–60,000 ohms (50–60 kΩ). An open reading means the thermistor is failed.
Because microwave thermistors have very high resistance values, make sure your multimeter is set to the correct range (usually the 200kΩ scale).
When to call a professional
Microwave repair involves exposure to high-voltage components including the magnetron and capacitor. Unless you have specific experience with microwave electronics, it is strongly recommended to have this repair done by a qualified appliance technician.
Related error codes
The temperature sensing thermistor has a short circuit.
Advanced Fix · 30–60 minutes
The touchpad or keypad membrane has a short circuit or stuck key.
Moderate Fix · 20–40 minutes
The control board has experienced an internal communication or memory error.
Professional Required · Professional service required
Information compiled from manufacturer service manuals, official troubleshooting documentation, and appliance repair industry resources. This guide is for informational purposes only — always consult a qualified technician for complex repairs.
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