LG Air Conditioner Error Code CH05 — Fix

What it means

LG Error Code CH05 means the indoor unit has lost communication with the outdoor unit.
A power reset clears CH05 caused by a power glitch.
If it returns, the communication wiring or a PCB requires professional inspection.

Affected Models

LG Artcool Series
LG Dualcool Series
LG Standard Plus Series
LG DUALCOOL Premium

Common Causes

Communication wiring between indoor and outdoor units loose or damaged
Indoor unit PCB communication fault
Outdoor unit PCB communication fault
Power surge disrupting communication settings

How to Fix It

Perform a full power reset.

Turn the AC off at the remote.
Turn off the circuit breaker or isolator supplying the indoor unit and wait 5 minutes.
Restore power and switch the unit on.
If CH05 was caused by a transient communication glitch, it will not return.
Inspect the communication cable connection.

The indoor and outdoor units connect via a communications cable (typically cores 3 and 4 in the inter-unit cable).
If accessible, check that the connector terminals are fully seated on both units.
Do not work on live wiring — isolate first.
Check for storm or surge history.

CH05 commonly follows a power surge or lightning strike.
Mention any recent electrical events to the technician — it helps identify which PCB is more likely affected.
Check the ThinQ app for more detail.

LG ThinQ-enabled units display additional diagnostic information in the app.
Open the LG ThinQ app, select the air conditioner, and check the Smart Diagnosis or error log section for any sub-codes.
Book an LG-authorised service agent.

Use the LG website to find a certified service agent.
Provide the CH05 code and any sub-codes.
CH05 repair typically involves testing both PCBs and the inter-unit wiring before replacing the faulty component.

When to Call a Professional

If a power reset does not clear CH05, the communication wiring or PCB has failed.
Contact an LG-authorised service agent — do not attempt to repair wiring without electrical qualifications.

Frequently Asked Questions

Can I reset LG Error CH05 without a service call?

A power reset is always worth trying first. If CH05 clears and does not come back within 24 hours, no further action is needed. If it returns immediately or within hours, the hardware fault needs professional repair.

Is LG Error CH05 covered under warranty?

LG split systems typically carry a 5-year warranty on parts and labour when installed by a licensed contractor. PCB failures caused by manufacturing defects are covered; those caused by power surges may require an insurance claim rather than a warranty claim.