LG Microwave F-2 Error: Shorted thermistor (temperature sensor short circuit)
LG microwave error — here’s what you need to know. The F-2 error code on your LG microwave indicates a shorted thermistor — the temperature sensor is reading an abnormally low resistance. This is a Medium severity issue. What Does F-2 Mean on an LG Microwave? The F-2 code is triggered when the control board […]
~30%
DIY Fixable
From $85
Typical Repair Cost
1–2 hours
Pro Repair Time
Quick Assessment
Answer to continue safely
Is it safe to keep using?
No. The unit will not heat while F-2 is active. Continued attempts to operate it can stress the control board. Stop using the appliance until the sensor circuit is confirmed to be in good condition.
Can I reset the code?
Yes. A power-off reset can clear a one-time F-2 caused by a genuine transient overheat. If the code reappears after the unit has fully cooled, a hardware fault is present and a reset will not provide a lasting fix.
When to stop immediately?
Stop if you notice: The code returns every time power is restored, even after the unit has fully cooled, You detect a burning or electrical smell when the microwave is powered on.
Symptoms You May Notice
Unit shuts down immediately when cooking is initiated
The microwave powers off within seconds of pressing Start, as the control board interprets the shorted sensor as an extreme overtemperature event.
F-2 error displayed at power-on or during operation
The display shows 'F-2' either when the unit first powers up or shortly after a cooking cycle begins.
Interior light and display work, but microwave will not heat
The control panel appears functional and responds to button presses, but the magnetron is disabled by the control board as a protective response to the sensor fault.
Inconsistent temperature performance
The microwave runs too hot, too cold, or cycles erratically because the control board receives inaccurate temperature readings from the faulty sensor.
Possible Causes
Thermistor shorted internally
The thermistor's internal resistance has collapsed to near zero due to heat damage or moisture, causing the control board to read an impossible temperature.
Requires ProfessionalPinched or chafed wiring harness
Wiring routed near sharp edges or hot components has worn through insulation, allowing conductors to short against each other or the chassis.
Requires ProfessionalFaulty control board misreading sensor input
The control PCB has developed a fault that causes it to register the thermistor input as a short even when the sensor and wiring are electrically sound.
Requires ProfessionalSafe Checks You Can Do
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1
Power-cycle reset
Unplug the microwave for 60 seconds to discharge any transient fault memory in the control board, then reconnect and test.
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2
Inspect the exterior vents for blockage
Ensure all ventilation slots on the top, sides, and rear of the unit are unobstructed. A restricted airflow can cause genuine overtemperature readings that mimic a shorted sensor.
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3
Allow the unit to cool completely
If the microwave was used heavily before the error appeared, let it sit unplugged for 30 minutes to cool, then retry — a genuine temporary overheat can produce an F-2 that resolves on its own.
When to Call a Professional
Contact a qualified technician if:
- Thermistor resistance measures near zero ohms at room temperature (should be approximately 10 kΩ–50 kΩ)
- Visible melting or discolouration on the wiring harness near the sensor
- Error persists after a confirmed-good replacement thermistor is installed
Need Professional Help?
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