Indoor unit displays CH02 and refuses to start or stops intermittently.

Safety warning: Disconnect power at the breaker before opening the indoor unit. Avoid touching live terminals.

Diagnostic and repair steps:

• Reset power: Turn the breaker OFF for 5 minutes, then ON. If CH02 reappears, proceed.
• Open indoor unit: Remove the front panel and filters, then remove the screws to access the coil and control board area.
• Locate the pipe thermistor: It is usually clipped directly to the evaporator coil tubing (small sensor head with two wires).
• Check mounting: Ensure the sensor is firmly clipped to the copper tube. If it has fallen off, reattach it securely; a loose sensor can trigger CH02.
• Inspect wiring: Follow the sensor wires back to the PCB. Look for cuts, pinches, or burn marks. Reseat the connector on the PCB.
• Measure resistance: With a multimeter, check resistance across the thermistor. Compare to LG service data if available; an open or short indicates failure.
• Replace sensor if needed: Install a new LG indoor pipe thermistor if the old one is defective. Route and secure wiring away from sharp metal edges and moving parts.
• Reassemble and test: Refit covers, restore power, and run the unit. Confirm CH02 is cleared and cooling is normal.

Call a professional if: The sensor and wiring are good but CH02 persists, as the indoor PCB or firmware may be faulty.