LG Air Conditioner Error Code CH03
The indoor unit and its wired wall controller have stopped talking to each other. A reset clears it when the cause was a glitch; a damaged cable or a wrong controller setting needs a technician.
Also shown as: 03, 3
Applies to: Residential wall-split and multi-split systems
Common causes
- Controller cable loose or damaged
- Controller set for the wrong control type (single instead of group, or the reverse)
- Indoor control board communication fault
- Electrical noise on the controller cable
What to check, in order
- Turn the unit off with the remote, then switch off its circuit breaker (or unplug it) and wait at least five minutes before switching back on.
- If several indoor units share one wall controller, check they all respond to it; a mis-set controller can trigger this code.
- If the code is still there after the reset, the cable and controller need professional testing.
Clear the code and test
- Fix what the checks above found first — a filter cleaned, an obstruction removed, the breaker restored. Clearing the code without fixing the cause only brings it back.
- Restore power at the breaker and switch the unit on with the remote.
- Run the unit in cooling or heating for ten to fifteen minutes and watch whether the code returns; some codes only appear after the compressor has run for a while.
- If the unit runs with no code, the fault is cleared. If the code returns, write down the code and whether the indoor or outdoor unit shows it before calling a technician — it speeds up the diagnosis.
When to call a professional
Most cases are solved by the checks above. Book a technician if any of these apply:
- The code comes back after you have run the checks and a test cycle.
- You smell burning, see sparks or scorch marks, or the breaker trips.
- Water is leaking and you cannot stop it.
- The fix needs panels opened beyond what your manual describes, or a part tested with a meter, and you are not set up for that.
When you call, give the brand, the code CH03, your model number (on a label on the side of the indoor unit) and the checks you already ran. It shortens the visit.
Parts that may be involved
Wired remote controllerIndoor control board
Parts are model-specific. Find your model number first — usually on a label on the side of the indoor unit — and match the part to that number before ordering.
Questions people ask about CH03
What does CH03 mean on a LG air conditioner?
CH03 means: Wired remote controller communication error. The indoor unit and its wired wall controller have stopped talking to each other. A reset clears it when the cause was a glitch; a damaged cable or a wrong controller setting needs a technician.
Can I fix LG CH03 myself?
Start yourself: the checks on this page cover the causes you can reach without opening the machine up. If they point to a faulty part, testing or replacing it is usually a technician job.
How do I clear LG CH03?
Fix what the checks above found first — a filter cleaned, an obstruction removed, the breaker restored. Clearing the code without fixing the cause only brings it back. Restore power at the breaker and switch the unit on with the remote. Run the unit in cooling or heating for ten to fifteen minutes and watch whether the code returns; some codes only appear after the compressor has run for a while.
Sources checked
The meaning and checks for this code were checked against the sources above in November 2026. Codes vary by model and region; if your manual lists a different meaning for your exact model, follow the manual.