LG Air Conditioner Error Code E122

E122 indicates that the indoor unit heat exchanger temperature sensor has an open or short circuit fault. The control board is not receiving a valid resistance signal from the thermistor that monitors coil temperature. This causes the unit to shut down to prevent unsafe operation. The fault can originate from the sensor itself, its wiring, or the indoor PCB.

No, you should not continue operating the unit with an active E122 error. The system relies on the heat exchanger sensor to regulate refrigerant and coil temperatures safely. Running without a valid sensor reading can lead to coil icing, compressor stress, or other component damage. Keep the unit off until the fault is diagnosed and corrected.

A power reset may temporarily clear the E122 code, but if the underlying sensor or wiring fault still exists, the error will return once the unit restarts and the PCB re-checks the sensor signal. A reset is useful as a first step after reseating a loose connector, but it is not a fix on its own. The root cause must be corrected for the error to stay cleared.

A knowledgeable DIYer can start by turning off all units, then inspecting the sensor connector at the indoor PCB for loose or corroded pins and reseating it. If the connector is secure, testing the thermistor with a multimeter and replacing the sensor if it reads open or shorted is within reach for someone comfortable with basic electrical work. However, if the PCB itself is suspect, professional service is recommended.

If only the temperature sensor needs replacement, parts typically cost in the range of $10 to $40 and labor, if a technician is involved, may add $75 to $150 depending on your region. If the indoor PCB is the root cause, board replacement can range from $100 to $300 or more for parts alone. Getting a proper diagnosis first avoids replacing parts unnecessarily.