LG Mini-Split Code CH12
Soft lockoutShown as: Indoor unit LED1 (units place) blinks 2 times and LED2 (tens place) blinks 1 time
Indoor unit middle pipe sensor error. The thermistor on the middle of the indoor coil is disconnected or shorted out.
Manual wording: “Indoor unit middle pipe thermistor has disconnected or has shorted out.”
Documented for: LSN091HSV / LSN121HSV and other LG single-zone indoor units fitted with a middle pipe sensor
Likely causes, most common first
- Sensor mis-wiring or short at the connector
- Moisture penetration into the sensor
- Bad sensor canning sheath (damaged sensor sheath or insulation)
- Sensor housing removed so the sensor is off the pipe
What you can safely check yourself
- Turn the system off at the breaker for one minute, then back on, to see if the code clears
When to call a technician
Thermistor replacement inside the indoor coil housing is a technician job.
A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Sources
- Defining Common Error Codes - Standard Wall-Mounted High-Efficiency Single Zone Systems (LG Electronics U.S.A. - Commercial Air Conditioning, LS091HSV and LS121HSV systems (LSN091HSV / LSN121HSV indoor units, LSU091HSV / LSU121HSV outdoor units)) · checked 2026-08-25
- Room Air Conditioner SVC Manual (General) - Trouble Shooting Guide with Error Code (LG Electronics, All LG single-zone room air conditioner / mini-split chassis (SW, SB, SC, S4, S5, SH, SA, SJ, SK)) · checked 2026-08-25