LG Refrigerator Error Code R2 R4 ON

The R2 R4 ON code means the refrigerator has detected an open or short circuit in one or both of its defrost sensors. These sensors are thermistors that monitor evaporator coil temperature during defrost cycles. When their resistance readings fall outside acceptable limits, the control board logs this error. The issue can affect defrost performance and lead to frost accumulation on the evaporator coils.

Continuing to run the refrigerator with this error active is not recommended for extended periods. A faulty defrost sensor can cause the evaporator coils to frost over completely, which will restrict airflow and reduce cooling performance. Food safety could be compromised if temperatures rise enough due to blocked airflow.

Unplugging the refrigerator for a few minutes may temporarily clear the error code from the display, but the code will return if the underlying sensor or wiring fault has not been corrected. A reset does not fix the hardware problem causing the fault. Proper diagnosis and repair of the defrost sensor circuit is required for a permanent resolution.

A knowledgeable DIYer can perform basic diagnosis by unplugging the refrigerator, accessing the evaporator panel, and using a multimeter to test each defrost sensor for proper resistance. If a sensor shows infinite resistance or near-zero resistance, it needs to be replaced. However, accessing the evaporator coils often requires removing panels and partially disassembling the refrigerator interior, which may be better handled by a technician.

If the defrost sensor itself is the problem, parts typically cost in the range of $15 to $50 per sensor, and the repair is relatively straightforward. If a technician is needed, total repair costs including labor generally fall between $100 and $250 depending on your location and the extent of the diagnosis required. Control board replacement, if needed, would cost significantly more.