If your LG mini split is flashing a CH code — like CH05 — the system has stopped and is telling you why. On units with a display, the code shows right on the indoor head or the wired controller. On units without a display, LG blinks the indoor LEDs to spell out the same 2-digit number. Once you read the code correctly, you'll know whether it's a simple drain or filter issue or a refrigerant/communication fault that needs a tech.
Reading the code: on models with a display, read the CHxx number directly. On models without one, LG uses the heat and cool indicator LEDs (LED1 / LED2) to blink out the two digits of the CH number — count the blinks to reconstruct it (for example, the pattern that resolves to "05"). This blink mapping varies by model family, so read your specific model's manual, and always confirm the code against the diagnostic label inside the indoor unit — control-board generations don't all use the same chart.
LG mini split CH error codes
| Code | Meaning | Typical cause |
|---|---|---|
| CH01 | Room (return-air) temperature sensor | Failed or disconnected indoor air thermistor |
| CH02 | Indoor pipe (coil) temperature sensor | Failed or loose indoor coil thermistor |
| CH04 | Drain pump / float switch | Clogged condensate drain, failed pump, or a stuck float switch |
| CH05 | Indoor-to-outdoor communication error (most common) | Loose or damaged connecting wiring between units, or a control/comms board |
| CH06 ⚠ | Sources vary — see note below | Some charts: indoor pipe outlet sensor. Others: an outdoor sensor. Verify on the unit. |
| CH07 | Conflicting operation mode (multi-split) | Indoor heads on one multi-split system set to opposing modes (one heating, one cooling) |
| CH10 | Indoor fan (BLDC) motor locked | Seized or obstructed indoor blower motor, or its wiring/board |
| CH38 (F4) ⚠ | Low refrigerant / gas leak | Refrigerant leak or undercharge — licensed-tech territory (EPA 608) |
About CH06: this is the code where charts disagree — some list it as the indoor pipe-outlet sensor, others as an outdoor sensor. We don't guess between them; we read the code on your board and verify against the diagnostic label inside your unit. Where two sources conflict, the label on your equipment is the authority.
What the codes are telling you
LG CH codes group into a few families:
- Communication (CH05). The most common LG code by far — the indoor and outdoor units can't talk. Usually a wiring problem at the terminal block, sometimes a board.
- Drain (CH04). The condensate isn't clearing — a clogged drain, tired pump, or stuck float. Often paired with water dripping from the head.
- Sensors (CH01, CH02, CH06). A thermistor reads out of range. These can be a genuinely failed sensor or just a loose connector.
- Airflow / fan (CH10). The indoor blower motor is locked or obstructed.
- Refrigerant (CH38 / F4). Low charge or a leak — this one goes to a licensed tech.
- Multi-split logic (CH07). Two heads fighting over heat vs. cool on the same system; set them to compatible modes.
Common causes
Most common first:
- Loose or damaged interconnecting wiring — the classic CH05 communication error.
- Clogged condensate drain or a failed pump/float — the CH04 code and dripping water.
- Refrigerant leak or undercharge — behind CH38/F4 and weak cooling.
- Failed thermistor — CH01, CH02, or CH06.
- Seized or obstructed indoor fan motor — CH10.
- A failed control/communications board — less common, but it can throw CH05 or intermittent codes.
The usual fix
Our tech reads the CH code, then confirms the cause rather than trusting the chart alone: check the interconnecting wiring and comms board on a CH05, clear and test the condensate drain and pump on a CH04, measure the thermistors on CH01/CH02/CH06, spin and inspect the indoor fan motor on CH10, and put gauges on the refrigerant circuit only when a CH38/F4 or the symptoms point there. Many calls end with a tightened connection or a cleared drain; when a board, motor, or the refrigerant circuit has genuinely failed, we repair it and confirm the unit holds setpoint through a full cycle.
DIY vs. calling a pro
Safe to try yourself first (free):
- Read and note the exact CH code (or the LED blink pattern) before doing anything.
- Wash the indoor filters and check the condensate drain line outdoors for a clog if you see a CH04 or dripping water.
- On a multi-split CH07, set all indoor heads to compatible modes (all heat or all cool) and retry.
- Power-cycle at the breaker to clear a soft fault after cleaning.
Call a pro when:
- You see CH05 that returns after checking the obvious, CH10, or any CH38/F4.
- The unit won't reach temperature, ices up, or leaks water after you've cleared the drain.
- Anything points to refrigerant. Refrigerant, compressor, and line-voltage electrical work must be handled by a licensed technician (EPA 608 certified for refrigerant handling) — the sealed system should never be opened otherwise.
What it costs in the Bay Area
Some CH codes cost only a diagnostic when the fix is a cleared drain, a tightened wire, or a mode change. When a part is needed, in our pricing a condensate pump/drain repair runs about $110–$350, a control/communications board $220–$700, and a refrigerant leak repair plus recharge $180–$700, depending on model and access. We charge a diagnostic fee that's credited toward the repair when you approve the work, with a firm, upfront price before anything begins.
Book LG mini split service
Triton services LG mini splits and Multi F systems — plus every major ductless brand — across the SF Bay Area & Peninsula, with same-week and often same-day appointments. If your LG is showing CH05 or another code, we'll read it correctly and get it running.
Call (888) 993-5699 or book online for ductless service.
Related pages
- HVAC Repair in the SF Bay Area — our full heating & cooling hub
- Mini Split Not Cooling — the symptom behind CH38/F4 and airflow codes
- Mini Split Not Heating — the heat-mode symptom
- Mini Split Service in Dublin — same-day service in your city
Frequently asked questions
What does CH05 mean on an LG mini split? CH05 is an indoor-to-outdoor communication error, and it is the most common LG code. The indoor and outdoor units cannot talk to each other. The usual cause is loose or damaged connecting wiring at the terminal block between the units, and sometimes a failed control or communications board. It needs a technician.
What does CH04 mean on an LG mini split? CH04 is a drain pump or float-switch fault. It usually means the condensate drain is clogged, the pump has failed, or the float switch is stuck, and it often comes with water dripping from the indoor head. Clearing the drain line frequently helps, but a failed pump or float switch needs replacement.
How do I read an LG mini split error code with no display? On units without a display, LG blinks the indoor heat and cool indicator LEDs to spell out the two digits of the CH number. Count the blink pattern to reconstruct the code, then confirm it against the diagnostic label inside the indoor unit, since the blink mapping varies by model family.
What does CH38 or F4 mean on an LG mini split? CH38, also shown as F4 on some systems, points to low refrigerant or a gas leak. The unit is undercharged or leaking. This is not a DIY fix. Refrigerant work must be done by a licensed technician who is EPA 608 certified to find the leak, repair it, and recharge the system correctly.
What does CH06 mean on an LG mini split? Sources vary on CH06. Some charts list it as the indoor pipe-outlet sensor, others as an outdoor sensor. We do not guess between them. We read the code on your specific board and confirm it against the diagnostic label inside your unit before acting, because control-board generations differ.
How much does LG mini split repair cost in the Bay Area? Some codes cost only a diagnostic when the fix is a cleared drain or a tightened wire. When a part is needed, a condensate pump or drain repair runs about 110 to 350 dollars, a control or communications board 220 to 700 dollars, and a refrigerant leak repair plus recharge 180 to 700 dollars. We credit the diagnostic fee toward the repair and quote a firm price first.