LG Refrigerator Error Code C/F-DEF-SEN

C/F-DEF-SEN means the refrigerator's self-diagnostic system has detected a failure in the defrost sensor circuit for the fresh food compartment. The sensor is responsible for monitoring temperature during the defrost cycle so the control board knows when to end defrost operation. The code is triggered when the sensor circuit reads either 0 ohms (short) or infinite ohms (open) at connector CN30, pins No.6 and No.7.

Short-term use is generally possible, but a non-functioning defrost sensor can cause the evaporator coils to ice over heavily, which will reduce cooling efficiency and may eventually stop airflow entirely. Over time this can lead to food spoilage or additional component damage. It is best to schedule a repair promptly rather than leaving the fault unaddressed.

Repair costs depend on the failed component. A replacement defrost sensor typically costs in the range of $15 to $50 for the part, while a wiring harness repair may be similar or less if only a connector is involved. Professional labor charges generally add $100 to $200 depending on your location and service provider. If the control board is at fault, costs will be considerably higher, often in the $200 to $400 range for parts and labor combined.

A knowledgeable DIYer can diagnose this code by checking resistance at CN30 pins No.6 and No.7 with a multimeter after disconnecting power. If the wiring is intact and the connector is clean and secure, the defrost sensor itself likely needs replacement. Wiring repairs and sensor replacements are within reach for those comfortable working around refrigerator components, but if the control board is suspected, professional diagnosis is recommended.

A power reset may temporarily clear the code from the display, but the fault will return as soon as the self-diagnostic cycle runs again if the underlying sensor or wiring problem has not been corrected. Resetting does not fix the hardware issue and should not be used as a substitute for proper diagnosis and repair.