LG Heat Pump Error Code E357

E357 indicates a 4-way valve operation error on your LG heat pump. The 4-way (reversing) valve is the component that switches the system between heating and cooling modes. The control board has detected that this valve is not operating as expected, which could be due to a failed solenoid coil, a stuck valve, wiring issues, or low refrigerant charge.

Continuing to operate the system with an active E357 fault is not advisable. A malfunctioning 4-way valve can cause the system to run in the wrong mode or place excessive strain on the compressor. Prolonged operation under these conditions can lead to compressor damage, which is a significantly more expensive repair.

A power cycle or reset may temporarily clear the E357 code, but if the underlying fault with the 4-way valve is still present, the error will return once the system attempts to switch operating modes. A reset alone does not fix the mechanical, electrical, or refrigerant issue causing the fault. Proper diagnosis and repair of the root cause are required for a lasting resolution.

Some basic checks, such as inspecting wiring connections to the 4-way valve solenoid, are within reach of a knowledgeable DIYer. However, testing solenoid coil resistance, checking system refrigerant pressures, and replacing the reversing valve all require specialized tools and, for refrigerant work, an EPA certification. It is strongly recommended to have a certified HVAC technician handle this repair.

Repair costs vary depending on the root cause. Wiring repairs may fall in the range of $75 to $200 in labor. A solenoid coil replacement typically costs between $100 and $300 including parts and labor. Full 4-way valve replacement is more involved and can range from $300 to $800 or more, depending on the unit and labor rates in your area.