LG Air Conditioner Error Code 126

Error code 126 on an LG air conditioner means the Sub1 outdoor unit's excessive cooling inlet temperature sensor has been detected as open or shorted. The control board cannot receive a valid signal from this sensor, so the system stops operating to prevent damage. The fault points to either the sensor itself, the connecting wiring, or the harness connector on the outdoor unit.

The system will generally shut itself down when this error is active, which is a protective response. You should not attempt to bypass the fault or force the unit to run, as operating without valid temperature sensor data can lead to compressor damage or unsafe operating conditions. Address the fault before resuming normal use.

Repair costs depend on what is actually faulty. A replacement inlet temperature sensor typically costs between $15 and $60 for the part, with labor adding $75 to $150 depending on your region and technician. If the outdoor control board needs replacement, total costs can range from $200 to $500 or more. Getting a diagnostic visit from a certified technician will confirm the exact failed component before committing to parts.

A knowledgeable DIYer can start by checking the sensor connector on the outdoor unit for looseness or visible corrosion and reseating it firmly. Measuring sensor resistance with a multimeter is also a straightforward check. However, replacing the sensor or diagnosing a control board fault typically requires familiarity with refrigeration systems and is best handled by a qualified technician.

A power reset may temporarily clear the displayed error, but if the underlying sensor or wiring fault is still present, the code will return once the system attempts to operate and reads the faulty sensor signal again. A reset alone does not fix the root cause and should only be used after the sensor or wiring issue has been resolved.