LG Air Conditioner Error Code 125

Error code 125 indicates the liquid pipe temperature sensor on the condenser side of the sub1 outdoor unit is reading as either open or shorted. This means the sensor's resistance is outside the range the control board expects for a functioning thermistor. The system flags this fault to prevent operating without accurate refrigerant temperature data. Diagnosis follows the same procedure used for error code 113.

It is not advisable to continue running the system with this error active. The liquid pipe sensor provides critical data used to manage refrigerant flow and subcooling at the condenser. Operating without accurate sensor input can lead to inefficient performance or potential system damage. The unit may also lock out automatically to prevent further issues.

A power reset may temporarily clear the error code, but if the underlying sensor or wiring fault is still present, the code will return once the unit runs through its self-diagnostic cycle. A reset without repair does not fix the root cause. Persistent return of the code after resetting confirms that a physical fault exists and must be addressed.

Basic checks like inspecting the sensor connector for looseness or visible corrosion can be done by a knowledgeable DIYer. However, testing thermistor resistance against a temperature-resistance chart and accessing the outdoor unit control board typically requires a technician with the proper tools. If the refrigerant circuit must be opened for any reason, a licensed HVAC technician is required.

If only the thermistor needs replacement, parts and labor costs typically range from around $75 to $200 depending on the unit and technician rates in your area. If the wiring harness or control board is involved, costs can rise to a range of $200 to $600 or more. Getting a diagnostic estimate before committing to repairs is recommended.