LG range shows F20 and oven may not heat or may shut off unexpectedly.

Safety first: Disconnect power at the breaker before testing.

• Test sensor resistance: Access the oven temperature sensor connector (rear of oven or behind control panel). At room temperature, the sensor should read ~1080 Ω. If reading is far outside spec, replace the sensor.
• Check connector: Ensure the sensor plug is fully seated and free of corrosion or burnt pins. Clean and reseat as needed.
• Inspect harness: Look for pinched or cut wires between the sensor and control board. Repair or replace damaged wiring.
• Control calibration: If the sensor and wiring are good, but F20 persists, the control board may be misreading the sensor. Replace the main control board.