LG Range Error Code F4

The F4 code on an LG range means the main oven temperature sensor has been detected in a shorted condition for more than one minute after a cook cycle starts. The sensor, also called a thermistor, is a probe inside the oven cavity that monitors temperature and should read approximately 1.09k ohms at room temperature. When it shorts, the resistance drops abnormally and the control board disables the oven. The fault must be resolved before normal cooking operation can resume.

The oven portion of the range should not be used while the F4 error is active. The code indicates the temperature sensor is not providing reliable readings, which means the oven cannot accurately regulate heat. Continuing to operate the oven under these conditions could result in overheating. Surface burners on a gas or electric range may still function normally, but oven use should be avoided until the fault is resolved.

Disconnecting power to the range for a few minutes and restoring it may temporarily clear the F4 code, but the error will return once a cook cycle starts if the underlying sensor fault has not been corrected. The control board triggers F4 after detecting a shorted sensor for over one minute during cooking, so the code is tied to an active hardware condition rather than a stored memory glitch. A reset is useful for confirming whether a connector seating issue resolved the problem, but it is not a permanent fix on its own.

Many homeowners and DIYers can address this repair with basic tools. Start by disconnecting power, then check the sensor connector at the back of the oven cavity for looseness or corrosion and reseat it. Use a multimeter to measure sensor resistance, comparing your reading to the expected value of approximately 1.09k ohms at room temperature. If the sensor reads significantly low, replacing the oven temperature sensor is a straightforward repair that typically involves removing one or two mounting screws and a wiring connector.

If the repair only requires a new oven temperature sensor, parts typically cost in the range of $20 to $60 depending on the specific model. If a professional technician is needed for diagnosis and installation, total repair costs including labor generally fall between $100 and $250. In less common cases where the main control board is at fault, parts alone can range from $150 to $350 or more, making professional diagnosis especially worthwhile before purchasing a board.