Microwave displays F3, often accompanied by erratic temperature or sensor cooking not working properly

Safety: Unplug the microwave before accessing internal components. Do not touch high-voltage areas.

• Check for obvious damage: Inspect the interior cavity for a loose or damaged temperature/sensor probe (if your Whirlpool model uses one for convection or sensor cooking).
• Access the sensor: Remove the outer cabinet (screws at back and sides). Locate the temperature or humidity sensor (often mounted in the cavity wall or top).
• Inspect wiring: Check the sensor harness and connector to the control board for loose plugs, broken wires, or corrosion. Reseat the connector.
• Test sensor (if you have a meter): With power disconnected, measure resistance across the sensor terminals and compare to Whirlpool service specs for your model. An open or shorted reading indicates a bad sensor.
• Replace faulty sensor: If the sensor is out of spec or physically damaged, replace it with the correct Whirlpool sensor probe or humidity sensor. Reassemble and test.
• Control board: If a known-good sensor and wiring are in place but F3 persists, the electronic control board may be defective and require replacement.