LG Air Conditioner Error Code CH12

CH12 indicates an open or short circuit fault in the middle pipe temperature sensor inside the LG indoor unit. The control board monitors this sensor continuously, and when the resistance signal falls outside the expected range, the system triggers CH12 and halts operation. The fault can be caused by a loose connector, damaged wiring, or a failed thermistor.

No, you should not continue operating the unit while CH12 is active. The middle pipe sensor provides data the system uses to prevent coil icing and protect the refrigerant circuit. Running the unit without reliable sensor input could lead to coil freeze-up, compressor stress, or additional component damage.

Repair costs vary depending on the root cause. If only a connector needs to be reseated, a service visit fee may be the primary cost, typically in the range of $75 to $150. If the middle pipe thermistor needs replacement, parts and labor combined generally fall in the range of $100 to $250. Control board replacement, if required, can increase that range significantly to $300 or more depending on the model.

A homeowner can safely check whether the sensor connector is fully seated, which resolves the error in some cases. However, testing thermistor resistance with a multimeter and tracing wiring for damage requires basic electrical knowledge and proper tools. Replacing the sensor or control board is best handled by a qualified technician to avoid misdiagnosis or further damage.

A power reset may temporarily clear the code, but CH12 will return if the underlying fault in the sensor, wiring, or connector has not been corrected. Resetting without addressing the root cause does not fix the problem and may delay a proper repair. The sensor and wiring should be inspected and tested before assuming the issue is resolved.