LG Air Conditioner Error Code 142

Error code 142 on an LG air conditioner indicates a communication failure between the main outdoor unit and the Sub2 outdoor unit in a three-unit system. The main outdoor unit is not able to successfully transmit data to the Sub2 unit, which prevents the units from coordinating their operation. The first step in diagnosing this error is to inspect the communication line connections between the two outdoor units.

Error code 142 itself does not indicate a hazardous condition such as a refrigerant leak or electrical short. It means the units cannot communicate and coordinate properly, which will prevent the system from operating normally. The system may shut down or operate in a limited mode to protect itself. There is no immediate safety risk to occupants from this specific fault code.

Repair costs depend on the root cause of the communication failure. If the fix involves reseating or replacing a damaged communication wire, costs are generally modest and may range from around $75 to $250 for a service call and minor wiring repair. If a communication PCB on one of the outdoor units needs replacement, costs can rise to the range of $300 to $700 or more depending on the part and labor involved. A technician will need to diagnose the specific failed component before an accurate estimate can be provided.

A homeowner can safely inspect the external communication wiring between outdoor units for visible damage, loose connections, or disconnected terminals without working on live electrical components. However, diagnosing or replacing a communication PCB inside an outdoor unit requires handling high-voltage components and should be performed by a qualified technician. If a simple wiring inspection does not resolve the issue, professional service is recommended.

A power reset may temporarily clear the error display, but if the underlying communication problem has not been corrected, the error will return once the system attempts to re-establish communication between units. A reset should only be used after the communication wiring and connections have been inspected and any faults corrected. Persistent reappearance of the code confirms that a hardware issue requires further diagnosis.