LG Refrigerator Error Code F-DEFROST SENSOR ERROR

This code means the Main PCB has detected a problem with the freezer defrost sensor circuit. The fault can be caused by a dislodged sensor, a cut or shorted wire, a contact defect at the connector, or a sensor that is reading a temperature outside its expected range. The refrigerator uses this sensor to control the defrost heater cycle, so an unresolved fault can lead to frost buildup on the evaporator and reduced cooling.

Short-term use is generally possible, but the fault means the freezer defrost cycle may not operate correctly. Over time, frost can accumulate on the evaporator coil, restricting airflow and causing the refrigerator and freezer sections to warm up. It is best to diagnose and repair the fault promptly to avoid food spoilage or secondary component damage.

Repair cost depends on the root cause. Replacing only the defrost sensor typically ranges from $40 to $120 for parts, with additional labor charges if a technician is hired. If the wiring harness requires repair or replacement, costs can range from $80 to $200 or more. Main PCB replacement, needed only if the board itself is at fault, is typically the most expensive option, ranging from $150 to $400 or higher depending on the model.

Start by checking the voltage at Main PCB connector CN30 between pins 2 and 4, which should read between 1.0V and 4.5V. If the voltage is out of range, inspect the sensor housing to confirm it is properly seated, then trace the wiring harness for cuts, shorts, or damaged insulation. If the wiring and connector check out, test the sensor element resistance directly and replace the sensor if it is out of specification.

A power reset may temporarily clear the code from the display, but the error will return if the underlying fault in the sensor circuit is not corrected. Because this code is tied to a measurable electrical condition at CN30, the control board will re-detect the problem during normal operation. A reset should only be used after completing repairs, to confirm the fault is resolved.