LG Mini-Split Code CH09
Hard lockoutShown as: Indoor unit LED1 (units place) blinks 9 times
Indoor unit EEPROM error. The memory chip on the indoor control board that stores the unit's model and setup data is unreadable, so the board does not know what unit it is controlling.
Manual wording: “Indoor unit EEPROM serial number marked on is 0 or FFFFFF.”
Documented for: All LG residential mini-split indoor units
Likely causes, most common first
- Poor connection of the option PCB
- Indoor unit EEPROM serial number reads 0 or FFFFFF (corrupted or blank memory chip)
What you can safely check yourself
- Turn the system off at the breaker for one minute, then back on
When to call a technician
CH09 is a control board / memory chip fault. The service manual's only remedy is to check the option PCB connection and replace the board - 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
- Single Zone Four-Way Ceiling-Cassette Installation Manual (LG Electronics U.S.A., Inc., Single-zone four-way ceiling cassette indoor units with LUU090HV through LUU420HV outdoor units) · checked 2026-08-25
- MULTI F / MULTI F MAX Outdoor Unit Installation Manual (LG Electronics U.S.A., Inc., Multi F and Multi F MAX multi-zone heat pump outdoor units (LMU series) with standard wall-mount, Art Cool, cassette and ducted indoor units) · checked 2026-08-25
- Convertible Mid-Static Ducted LGRED Degree System Installation Manual (LG Electronics U.S.A., Inc., LGRED single-zone convertible mid-static ducted indoor units with LUU180HHV / LUU240HHV outdoor units) · checked 2026-08-25
- 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