LG Refrigerator Error Code fS

The fS code on an LG refrigerator indicates a freezer compartment sensor failure. Specifically, it means the freezing room thermistor has either a short circuit or an open circuit condition. The control board uses voltage readings at a specific test point to determine which type of fault is present: 0V signals a short, and 5V signals an open circuit.

When the fS code is active, the freezer temperature sensor is not functioning reliably, which means the refrigerator cannot accurately monitor or regulate freezer temperatures. Continuing to store frozen food carries the risk of undetected temperature rises and potential spoilage. It is best to address the fault promptly and avoid relying on the freezer for critical food storage until it is resolved.

A power reset, such as unplugging the refrigerator for a few minutes and plugging it back in, may temporarily clear the fS code if the fault was caused by a momentary glitch or a loose connector that reseats itself. However, if the thermistor or wiring has a genuine failure, the code will return once the control board re-evaluates the sensor signal. A persistent fS code requires physical diagnosis and likely a component repair or replacement.

A knowledgeable DIYer can attempt some diagnostic steps, such as inspecting the wiring harness for visible damage, reseating connectors, and testing voltage and resistance with a multimeter. If the thermistor itself has failed, replacing it is a straightforward part swap in most cases. However, if the fault traces back to the main control board, professional repair is recommended.

Repair costs depend on the root cause. A replacement freezer thermistor typically costs between $10 and $40 for the part alone. If professional labor is required, total repair costs including the part can range from $100 to $250 or more. A main control board replacement, if needed, will push costs higher, often into the $200 to $400 range for parts and labor combined.