LG Oven Error Code F4 — Shorted Sensor (Lower Oven Thermistor)
What this means
The F4 error code means the lower oven temperature sensor (thermistor) has been shorted for over 1 minute during cooking. A shorted sensor reads near-zero resistance, telling the control board the oven is extremely hot when it may not be. This can be caused by insulation breakdown in the sensor, water intrusion, or a pinched wire.
Step-by-step fix
3 stepsReset the oven
Press CLEAR/OFF. Turn off the circuit breaker for 30 seconds, then turn it back on.
Test the sensor
Using a multimeter, measure resistance across the sensor leads. A shorted sensor reads near 0 ohms instead of the normal ~1080 ohms at room temperature. Replace if shorted.
Inspect the wiring
Check the sensor wires for pinching, melting, or bare spots that could cause a short circuit.
When to call a professional
If the sensor and wiring look fine but the error persists, the main control board may have a failed input circuit.
Related error codes
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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