LG Air Conditioner Error Code CH05
The indoor and outdoor units have lost their data link, so the system stops a few minutes after starting. Power problems and wiring faults are the usual causes, and one reset is worth trying before calling a technician.
Also shown as: 05, 5, C5
Applies to: Residential wall-split and multi-split systems
Common causes
- Breaker tripped or power lost to one of the units
- Interconnecting cable loose, damaged or wrongly wired
- Indoor or outdoor control board fault
- Electrical noise interfering with the signal cable
What to check, in order
- Check the breaker panel and any outdoor isolator switch: both units need power for the link to work.
- 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.
- Note whether the code appears a few minutes after switching on; that timing is useful information for the technician.
- If both units have power and the code returns, stop there: the cable and boards 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 CH05, 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
Indoor control boardOutdoor 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 CH05
What does CH05 mean on a LG air conditioner?
CH05 means: Communication error between indoor and outdoor units. The indoor and outdoor units have lost their data link, so the system stops a few minutes after starting. Power problems and wiring faults are the usual causes, and one reset is worth trying before calling a technician.
Can I fix LG CH05 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 CH05?
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.