LG Air Conditioner Error Code 71

Error code 71 on an LG air conditioner indicates a converter CT sensor error in the outdoor unit. The CT sensor monitors electrical current in the inverter or compressor circuit, and the control board has detected a signal that is missing or out of range. The system shuts down as a protective measure to prevent damage to the compressor and drive components.

No. Error code 71 causes the system to shut down automatically because continued operation without accurate current monitoring could damage the compressor or inverter drive. You should leave the unit off until the fault is diagnosed and repaired. Attempting to force operation could result in more extensive and costly damage.

Repair costs vary depending on the root cause. Wiring repairs or connector replacements are generally on the lower end, typically in the range of $75 to $200 including labor. A replacement CT sensor will add parts cost on top of labor. If the inverter control board requires replacement, total costs can range from $300 to $700 or more depending on the model and local labor rates.

Some basic checks, such as inspecting visible wiring and reseating connectors on the outdoor unit, can be done by a knowledgeable homeowner. However, the CT sensor is located near high-voltage inverter components, and proper diagnosis requires a multimeter and familiarity with electrical safety procedures. In most cases, a qualified HVAC technician should handle this repair to avoid risk of electric shock.

A power reset may temporarily clear the error and allow the unit to restart, but if the underlying sensor, wiring, or board issue is not resolved, the code will return. Repeated resets without repair can stress components further. A reset should only be used as part of a diagnostic process, not as a long-term solution.