LG Refrigerator Error Code Error4

Error4 indicates the control board has detected an abnormal reading from the defrost sensor circuit, either a short circuit or an open circuit. The defrost sensor is a thermistor located near the evaporator coils that tells the board when to end the defrost heating cycle. When this sensor or its wiring fails, the board logs Error4 and normal defrost operation may be disrupted. Resistance should be checked at CON7 PIN 3 and PIN 4 to begin diagnosing the fault.

The refrigerator may continue to run, but without a functioning defrost sensor the appliance cannot properly regulate the defrost cycle. This can lead to ice buildup on the evaporator coils over time, which reduces cooling efficiency and can eventually cause the refrigerator to stop cooling adequately. It is best to address Error4 promptly to prevent food spoilage and potential secondary damage to other components.

If the defrost sensor is the failed component, the part itself typically costs in the range of $15 to $50 depending on the specific model. If you hire a technician, total repair costs including labor generally fall in the range of $100 to $200. Costs can be higher if the wiring harness is also damaged and requires replacement or splicing in addition to the sensor.

A knowledgeable DIYer can diagnose this error by using a multimeter to check resistance at the defrost sensor connector, CON7 PIN 3 and PIN 4. If the wiring is intact and the sensor itself reads open or shorted, replacing the defrost thermistor is a straightforward repair involving unplugging the old sensor and connecting the new one. However, accessing the evaporator and sensor typically requires removing the freezer back panel, so comfort with appliance disassembly is helpful.

A reset may temporarily clear the error display, but the code will return if the underlying fault with the defrost sensor or its wiring has not been corrected. The control board continuously monitors the sensor circuit, so any persistent open or short condition will trigger Error4 again after the reset. A proper repair to the sensor or harness is required for the error to clear permanently.