LG Air Conditioner Error Codes: Complete Guide & Fixes

LG air conditioners are designed with advanced sensors and diagnostics that make them reliable. But when something goes wrong, your AC will usually display an error code to point you in the right direction.

These codes may look confusing at first, but once you know what they mean, they can save you time, reduce downtime, and help you decide whether it’s a simple fix or if you need a technician.

This complete guide covers:

• How LG error codes work
• Full list of LG AC error codes (split, inverter, multi, portable & window units)
• Causes and troubleshooting steps
• When to call a professional

How LG Error Codes Work

• Codes are shown on the indoor unit display, remote controller, or through LED blinking lights on certain models.
• Most LG systems use the CH (Check) format (e.g., CH05, CH38). Portable and window units may use E or P codes.
• The error code tells you what part of the system is at fault: sensor, fan, compressor, refrigerant pressure, communication, or power.

Full List of LG Air Conditioner Error Codes

Below is the complete list of LG error codes across different unit types.

CH / C Series Codes

• CH01 – Indoor air sensor fault
• CH02 – Indoor pipe sensor fault
• CH03 – Outdoor pipe sensor fault
• CH04 / FL – Drainage problem (water full, float switch, pump, blocked drain)
• CH05 / C5 – Communication error between indoor & outdoor unit
• CH06 – Indoor/outdoor unit mismatch or inverter EEPROM error
• CH07 – Multi-system mode conflict (heating vs cooling at same time)
• CH08 – Indoor fan motor fault
• CH09 – EEPROM error (indoor PCB data issue)
• CH10 – Outdoor fan motor fault
• CH11 – Communication error between indoor unit and wired remote
• CH12 – Indoor pipe sensor (secondary) fault
• CH13 – Indoor/outdoor capacity mismatch
• CH21 – DC peak (overcurrent / power transistor protection triggered)
• CH22 – Voltage abnormality / AC low voltage
• CH23 – DC link low voltage
• CH26 – DC compressor position detection error / inverter problem
• CH27 – Over-voltage / high DC voltage
• CH28 – Current sensor fault
• CH32 – Outdoor unit capacity setting error
• CH33 – High pressure switch trip (system pressure too high)
• CH34 – Low pressure switch trip (system pressure too low / shortage of gas)
• CH35 – Discharge pipe temperature high
• CH38 – Low refrigerant / gas shortage detected
• CH41 – Outdoor discharge pipe thermistor error
• CH44 – Outdoor suction pipe sensor error
• CH45 – Inverter compressor discharge sensor error
• CH46 – Inverter compressor suction sensor error
• CH47 – Outdoor heat sink sensor error
• CH51 – Capacity mismatch (indoor vs outdoor)
• CH52 – Phase loss / wrong wiring (for 3-phase units)
• CH53 – Current imbalance (3-phase units)
• CH54 – Inverter power module fault
• CH60 – Outdoor air temperature sensor fault
• CH61 – Outdoor unit over-heating (airflow problem, ambient temp too high)
• CH62 – Outdoor fan motor sensor error
• CH65 – Outdoor heat exchanger middle sensor error
• CH66 – Outdoor unit communication error
• CH67 – Outdoor fan motor fault (BLDC fan error)
• CH70 – EEPROM error in outdoor unit
• CH71 – Inverter compressor motor fault
• CH72 – Inverter compressor stalling / locked
• CH73 – Discharge temperature sensor error (outdoor)
• CH74 – Suction temperature sensor error (outdoor)
• CH75 – Discharge superheat error
• CH76 – Low pressure switch open
• CH77 – Pressure sensor error (outdoor PCB)
• CH78 – High pressure sensor fault (refrigerant overcharge, blocked condenser)
• CH79 – Inverter CT (current transformer) error
• CH80 – Outdoor EEPROM error
• CH81 – Communication error between outdoor units (multi-system)
• CH90 – Indoor communication error with master PCB
• CH91 – Master/Slave communication error
• CH92 – Communication error between indoor units in group control
• CH93 – Wired remote communication error

P / F / E Series (Some LG models use these)

• P1 – Indoor unit EEPROM error
• P2 – Indoor pipe thermistor open/short
• P3 – Outdoor pipe thermistor error
• P4 – Drain pump / water level sensor error
• P5 – DC fan motor fault
• P6 – Freezing / Overheating safeguard
• P7 – Outdoor condenser coil sensor error
• P8 – Outdoor discharge sensor error
• F1–F3 – Indoor fan step error (1, 2, or 3)
• F4 – Outdoor fan error
• F5 – DC motor communication error
• E1 – Communication error (indoor ↔ outdoor)
• E2 – Indoor temperature sensor fault
• E3 – Indoor coil sensor fault
• E4 – Outdoor temperature sensor fault
• E5 – Overcurrent / compressor error
• E6 – Communication fault (multi-split system)
• E7 – Mode conflict between units

Portable & Window Unit Codes

• FL – Water tank full (drain the tank)
• E1 – Room sensor open/short
• E2 – Coil sensor open/short
• E3 – Comp/Overload / Compressor protection
• E4 – Indoor airflow error
• P2 – Water tray full (portable ACs)

Troubleshooting Tips

• Power cycle: Turn off the AC at the breaker for 5–10 minutes, then restart.
• Clean filters & coils: Clogged filters are a major cause of freeze and airflow errors.
• Check drainage: Clear any blockages in condensate lines or empty the water tank.
• Inspect wiring: Look for loose plugs, damaged cables, or corroded connectors.
• Check outdoor unit: Remove debris, ensure fan spins freely, and confirm airflow is not blocked.
• Verify settings: In multi-systems, ensure all units are set to the same mode.

When to Call a Technician

• Refrigerant errors (CH38, CH33, CH34, CH78)
• Compressor or inverter module faults (CH21, CH54, CH71)
• Persistent communication issues (CH05, CH66, CH93)
• Any error that keeps recurring after reset

Preventing Error Codes

• Regular maintenance (filter cleaning, coil cleaning)
• Annual servicing to check refrigerant and electrical systems
• Keep outdoor unit clear of debris and with good airflow
• Use surge protection to protect PCB and inverter circuits

Conclusion

LG air conditioner error codes are not random they’re diagnostic tools. Understanding them helps you troubleshoot quickly, fix minor issues yourself, and know when to bring in a professional.

If you provide me your LG AC model number, I can refine this list into a model-specific error code reference for even more accurate troubleshooting.