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Error code reference

Whirlpool Microwave Error Code F3T

Temperature sensor out of range.

Whirlpool codesWhirlpool microwave codes

Temperature sensor out of range.

First step from the service manual

Unplug microwave oven or disconnect power, then replace electronic control.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What F3T means on a Whirlpool microwave

The F3T error code on a Whirlpool microwave indicates that the temperature sensor is reading outside of its expected operating range. The temperature sensor, sometimes called a cavity thermistor, monitors the internal temperature of the microwave cavity and provides feedback to the electronic control board. When the control board receives a signal that falls outside the acceptable voltage or resistance parameters, it interprets this as a fault condition and displays the F3T code to prevent potential overheating or unsafe operation.

The most common causes of this fault are either a failed temperature sensor or a failed electronic control board. A damaged sensor may present as an open circuit or a short, both of which send an out-of-range reading to the control. Wiring harness issues such as a loose connector or damaged wires between the sensor and the control board can produce the same symptom. Because the sensor and control board are interdependent in this diagnostic loop, a fault in either component will trigger the same code.

The prescribed first diagnostic step is to disconnect power to the unit and replace the electronic control board. This approach reflects that the control board is the component responsible for interpreting the sensor signal, and a faulty board may misread a healthy sensor as out of range. If board replacement does not resolve the fault, the temperature sensor itself should be inspected and tested for continuity and proper resistance values before replacing it.

Source: manufacturer service documentation.

Common causes of F3T

  1. 01

    Failed electronic control board

    Part replacement

    The control board may be misinterpreting the temperature sensor signal due to internal component failure. Because the first diagnostic step points directly to control board replacement, this is the primary suspect.

  2. 02

    Defective temperature sensor

    Part replacement

    The temperature sensor itself may have failed in an open or shorted state, sending a voltage or resistance reading outside the acceptable range to the control board. Testing the sensor for proper continuity and resistance can confirm this cause.

  3. 03

    Loose or damaged wiring harness

    Wiring / connection

    A disconnected, corroded, or damaged connector between the temperature sensor and the control board can interrupt the signal and trigger an out-of-range fault. Visually inspect the wiring and connectors for damage or loose seating.

  4. 04

    Thermal damage to sensor from overheating

    Part replacement

    Prolonged overheating inside the cavity can physically damage the temperature sensor. Check for signs of discoloration or melting near the sensor mounting location.

See the test procedure for each cause

Frequently asked questions about F3T

What does F3T mean on a Whirlpool microwave?
The F3T code on a Whirlpool microwave means the temperature sensor is reading outside of its expected range. The electronic control board monitors the sensor signal continuously, and when that signal falls outside acceptable parameters, the unit faults and displays F3T. This is a protective measure to prevent unsafe operation due to inaccurate temperature monitoring.
Can I fix the F3T error code myself?
The first recommended step is to unplug the microwave and replace the electronic control board. This is a repair that requires comfort working with appliance electronics and proper safety precautions, as microwave capacitors can hold a lethal charge even after being unplugged. If you are not experienced with appliance repair, having a qualified technician handle this job is strongly advised.
Is it safe to use my Whirlpool microwave when it shows F3T?
No, you should not continue using the microwave while the F3T fault is active. The code indicates the temperature sensor is not functioning correctly, which means the appliance cannot accurately monitor its internal temperature. Continuing to operate it could pose an overheating or safety risk.
Will resetting the microwave clear the F3T error?
Unplugging the microwave and restoring power may temporarily clear the display, but the F3T code will return if the underlying component failure is not addressed. A reset does not repair a failed control board or temperature sensor. Proper diagnosis and part replacement are required for a lasting fix.
How much does it cost to repair a Whirlpool microwave with an F3T error?
Repair costs depend on which component has failed. A replacement electronic control board typically ranges from $50 to $150 or more for the part alone, and professional labor can add $75 to $150 to that total. If the temperature sensor is the root cause, parts are generally less expensive, but diagnosis fees may still apply. Getting a technician estimate before committing to repairs is a good idea, especially on older units.

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