LG Heat Pump Error Code E161

E161 indicates that the first MCU has detected the solenoid valve for cooling and heating in the open position at the same time. This is a refrigerant circuit control fault where conflicting commands are being sent or read by the main control unit. The system flags this error to prevent damage from operating the refrigerant circuit in an undefined state. A technician needs to diagnose whether the fault originates in the MCU board, the wiring harness, or the solenoid valve itself.

It is not recommended to continue operating the heat pump while E161 is active. The error indicates a conflict in the refrigerant circuit switching logic, and running the system in this state could cause compressor stress or refrigerant circuit issues. The unit should be shut down and inspected before restarting.

Repair costs depend on the root cause identified during diagnosis. Wiring repairs or connector replacements are typically on the lower end of the cost range. Solenoid valve coil replacement generally falls in a mid-range cost. MCU control board replacement is usually the most expensive repair, with parts and labor potentially ranging from several hundred to over a thousand dollars depending on the model and local labor rates.

Basic checks like inspecting the wiring harness for visible damage, pinched wires, or loose connectors can be done by a knowledgeable DIYer. However, testing MCU output signals and diagnosing the solenoid valve coil requires a multimeter and familiarity with control board circuits. Replacing the MCU or solenoid valve involves refrigerant system work and high-voltage components, which should be handled by a licensed technician.

A full power reset by turning off the unit at the circuit breaker for several minutes may temporarily clear the error if the fault was caused by a transient MCU logic state. However, if the underlying cause is a wiring short, faulty solenoid valve coil, or damaged MCU board, the error will return after the system restarts. Persistent recurrence means the root hardware fault must be repaired.