Try DIY first — may need a proVerified by FixOffice
LG CH 05 — Indoor/outdoor communication error
Applies to: LG mini-split and multi-split systems
What this error means
LG's communication fault between indoor and outdoor units — same family as Mitsubishi E6 and Daikin U4. Wiring, power, or board.
Symptoms
- CH 05 (or CH05) on display
- Unit stops responding
Try this first (safe DIY steps)
- Full power cycle at the breaker, 3–5 minutes off
- Verify outdoor unit power
- Log recurrence timing for the tech
Safety: power off before any physical intervention. Never bypass covers or interlocks — fuser areas run hot enough to burn.
When to call a technician
On recurrence — communication-line and PCB diagnosis.