LG Oven Error Code F-5

F-5 means the lower oven thermistor has been detected in a shorted condition for more than one minute after a cook cycle starts. The thermistor is the temperature sensor inside the lower oven cavity, and when it shorts, it sends an invalid signal to the control board. The board shuts down the cook cycle and displays F-5 to prevent uncontrolled or unsafe heating.

No, it is not safe to use the oven while F-5 is active. The error indicates the control board is receiving a faulty temperature reading from the lower oven sensor, which means the oven cannot properly regulate its heating elements. Using the oven in this condition could result in overheating or unpredictable temperature behavior.

If the fault is limited to the lower oven thermistor, parts typically range from around $20 to $60 depending on the specific model, and the repair is relatively straightforward for a technician. If the wiring harness is damaged or the control board is involved, total repair costs including labor could range from $100 to $300 or more. Getting a professional diagnostic first can help identify exactly which component has failed before purchasing parts.

Resetting the oven by cutting power may temporarily clear the display, but the F-5 error will return as soon as a cook cycle starts if the underlying fault still exists. Because the error is triggered by a sustained shorted signal from the thermistor, the root cause needs to be diagnosed and corrected. Operating the oven with a faulty temperature sensor is not recommended, as the control board cannot accurately regulate heat.

Start by entering test mode 4 and checking that the sensor value reads between 70°F and 90°F at room temperature. If the value is outside that range, power off the oven and use a multimeter to measure thermistor resistance at connector CN05. A normal reading is approximately 1.09 kΩ at room temperature. A reading significantly below that value confirms a shorted thermistor or wiring fault.