LG Aircon Error Codes

Reference table for common LG codes. Use it to understand likely meaning, typical causes, and context before booking.

Before you use this tool

This is a guidance table, not a model-exact diagnosis. The same code can differ by series, controller, and model year. Use this page to narrow next steps, then verify with model sticker details.

Safety warning

Stop using the unit and contact a technician if the breaker trips repeatedly, you smell burning, see sparks, hear loud electrical buzzing, or water is leaking from places it normally should not.

LG code table

Includes common SG residential split-system codes with likely meaning and typical causes.

CH00System

General fault indication requiring inspection

Typical causes

Temporary power fluctuation or electrical noise
Startup self-check detected abnormal condition
Underlying fault pending full diagnosis

CH01Sensor

Indoor air temperature sensor open/short

Typical causes

Thermistor or sensor open/short circuit
Loose sensor connector or damaged harness
Sensor out-of-range due to heat/moisture stress
Control PCB sensor input fault

CH02Sensor

Indoor pipe temperature sensor open/short

Typical causes

Thermistor or sensor open/short circuit
Loose sensor connector or damaged harness
Sensor out-of-range due to heat/moisture stress
Control PCB sensor input fault

CH03System

Refrigerant absence or severe refrigerant-flow abnormality

Typical causes

Refrigerant shortage due to leak at flare joint or piping
Restriction in expansion valve or refrigerant circuit
Compressor protection triggered by low suction condition

CH04Indoor

Drainage/full-water-level error

Typical causes

Drain pump not operating or drain path blocked
Condensate tank or drain pan reached full level
Float switch/level sensor abnormality

CH05Communication

Communication error between indoor and outdoor units

Typical causes

Loose, reversed, or damaged communication wiring between indoor and outdoor units
Poor terminal contact or corroded wire joints
Indoor or outdoor PCB communication circuit fault
Power instability during operation or after installation

CH06Sensor

Outdoor pipe temperature sensor open/short

Typical causes

Thermistor or sensor open/short circuit
Loose sensor connector or damaged harness
Sensor out-of-range due to heat/moisture stress
Control PCB sensor input fault

CH07System

Operating-mode conflict across connected indoor units

Typical causes

Connected indoor units are set to conflicting operation modes
One unit in heating while another is in cooling/dehumidify mode
Mode state mismatch after power recovery in multi-split system

CH09Indoor

Indoor PCB/control board fault

Typical causes

Indoor control board, fan, or drainage component fault
Loose connectors or internal wiring issue
Drain blockage, float-switch, or pump abnormality
Airflow restriction causing protection trip

CH10Indoor

Indoor BLDC fan motor lock or fan drive fault

Typical causes

Indoor BLDC fan motor locked or failing
Fan wheel jammed by dirt/debris
Fan motor drive circuit or indoor PCB fault
Wiring harness or connector loosened

CH12Sensor

Indoor thermistor disconnected/abnormal

Typical causes

Thermistor or sensor open/short circuit
Loose sensor connector or damaged harness
Sensor out-of-range due to heat/moisture stress
Control PCB sensor input fault

CH21Inverter

Compressor overcurrent / IPM protection

Typical causes

Inverter IPM/power module abnormality
Compressor electrical overload or lock condition
DC link voltage/current abnormality
Power fluctuation causing inverter protection trip

CH22Inverter

Current sensing value too high (CT protection)

Typical causes

Inverter IPM/power module abnormality
Compressor electrical overload or lock condition
DC link voltage/current abnormality
Power fluctuation causing inverter protection trip

CH23Inverter

Low DC link voltage in inverter circuit

Typical causes

DC link voltage dropped below safe threshold
Inverter module or capacitor deterioration
Power supply sag or unstable mains voltage

CH24Outdoor

Pressure switch or pressure protection fault

Typical causes

Condenser airflow blocked or outdoor coil heavily dirty
Outdoor fan motor/driver abnormality
Refrigerant pressure or flow imbalance
Outdoor control board protection triggered

CH25Inverter

AC input voltage abnormal (high/low)

Typical causes

Inverter IPM/power module abnormality
Compressor electrical overload or lock condition
DC link voltage/current abnormality
Power fluctuation causing inverter protection trip

CH26Inverter

Compressor position/drive abnormal

Typical causes

Inverter IPM/power module abnormality
Compressor electrical overload or lock condition
DC link voltage/current abnormality
Power fluctuation causing inverter protection trip

CH27Inverter

Power/current sensing circuit fault (PSC)

Typical causes

Inverter IPM/power module abnormality
Compressor electrical overload or lock condition
DC link voltage/current abnormality
Power fluctuation causing inverter protection trip

CH28Inverter

DC link high-voltage protection

Typical causes

Inverter IPM/power module abnormality
Compressor electrical overload or lock condition
DC link voltage/current abnormality
Power fluctuation causing inverter protection trip

CH29Inverter

Compressor overcurrent protection

Typical causes

Inverter IPM/power module abnormality
Compressor electrical overload or lock condition
DC link voltage/current abnormality
Power fluctuation causing inverter protection trip

CH31Inverter

Inverter compressor over-temperature protection

Typical causes

Inverter IPM/power module abnormality
Compressor electrical overload or lock condition
DC link voltage/current abnormality
Power fluctuation causing inverter protection trip

CH32Outdoor

Compressor discharge temperature too high

Typical causes

Condenser airflow blocked or outdoor coil heavily dirty
Outdoor fan motor/driver abnormality
Refrigerant pressure or flow imbalance
Outdoor control board protection triggered

CH33Sensor

Discharge temperature sensor open/short

Typical causes

Thermistor or sensor open/short circuit
Loose sensor connector or damaged harness
Sensor out-of-range due to heat/moisture stress
Control PCB sensor input fault

CH34Outdoor

High-pressure protection activated

Typical causes

High condensing pressure from blocked outdoor airflow
Outdoor coil heavily soiled or fan underperforming
Refrigerant overcharge or non-condensable gas in circuit

CH35Outdoor

Low-pressure protection activated

Typical causes

Condenser airflow blocked or outdoor coil heavily dirty
Outdoor fan motor/driver abnormality
Refrigerant pressure or flow imbalance
Outdoor control board protection triggered

CH36Outdoor

Compressor discharge temperature protection (outdoor)

Typical causes

Condenser airflow blocked or outdoor coil heavily dirty
Outdoor fan motor/driver abnormality
Refrigerant pressure or flow imbalance
Outdoor control board protection triggered

CH37Outdoor

Low-pressure switch open fault

Typical causes

Condenser airflow blocked or outdoor coil heavily dirty
Outdoor fan motor/driver abnormality
Refrigerant pressure or flow imbalance
Outdoor control board protection triggered

CH38System

Refrigerant shortage (low gas) detected

Typical causes

Low refrigerant charge from leak in piping or flare joints
Service valves not fully opened after installation/relocation
Refrigerant flow restriction causing low-pressure condition

CH39Sensor

PCB or CT sensor open/abnormal

Typical causes

Thermistor or sensor open/short circuit
Loose sensor connector or damaged harness
Sensor out-of-range due to heat/moisture stress
Control PCB sensor input fault

CH40Sensor

Current transformer (CT) sensor open/short

Typical causes

Thermistor or sensor open/short circuit
Loose sensor connector or damaged harness
Sensor out-of-range due to heat/moisture stress
Control PCB sensor input fault

CH41Sensor

Compressor discharge thermistor open/short

Typical causes

Thermistor or sensor open/short circuit
Loose sensor connector or damaged harness
Sensor out-of-range due to heat/moisture stress
Control PCB sensor input fault

CH44Sensor

Outdoor air thermistor open/short

Typical causes

Thermistor or sensor open/short circuit
Loose sensor connector or damaged harness
Sensor out-of-range due to heat/moisture stress
Control PCB sensor input fault

CH45Sensor

Outdoor middle-pipe thermistor open/short

Typical causes

Thermistor or sensor open/short circuit
Loose sensor connector or damaged harness
Sensor out-of-range due to heat/moisture stress
Control PCB sensor input fault

CH46Sensor

Outdoor suction-pipe thermistor open/short

Typical causes

Thermistor or sensor open/short circuit
Loose sensor connector or damaged harness
Sensor out-of-range due to heat/moisture stress
Control PCB sensor input fault

CH48Sensor

Compressor discharge-pipe thermistor open/short

Typical causes

Thermistor or sensor open/short circuit
Loose sensor connector or damaged harness
Sensor out-of-range due to heat/moisture stress
Control PCB sensor input fault

CH53Communication

Communication error between main and sub PCB

Typical causes

Loose or damaged interconnection cable between indoor and outdoor units
Poor terminal contact or wiring corrosion
Indoor or outdoor PCB communication circuit fault
Power supply instability

CH54System

Phase/reverse-phase power wiring error

Typical causes

Reverse phase sequence (R/S/T) after electrical work
One supply phase missing at outdoor unit terminal
Incorrect breaker-box wiring to dedicated AC circuit

CH60Outdoor

Outdoor EEPROM or memory fault

Typical causes

Condenser airflow blocked or outdoor coil heavily dirty
Outdoor fan motor/driver abnormality
Refrigerant pressure or flow imbalance
Outdoor control board protection triggered

CH61Outdoor

Condenser/heat-exchanger over-temperature protection

Typical causes

Condenser airflow blocked or outdoor coil heavily dirty
Outdoor fan motor/driver abnormality
Refrigerant pressure or flow imbalance
Outdoor control board protection triggered

CH62Inverter

Inverter heatsink temperature too high

Typical causes

Inverter IPM/power module abnormality
Compressor electrical overload or lock condition
DC link voltage/current abnormality
Power fluctuation causing inverter protection trip

CH63Sensor

Condenser pipe sensor open/short

Typical causes

Thermistor or sensor open/short circuit
Loose sensor connector or damaged harness
Sensor out-of-range due to heat/moisture stress
Control PCB sensor input fault

CH65Sensor

Heatsink temperature sensor open/short

Typical causes

Thermistor or sensor open/short circuit
Loose sensor connector or damaged harness
Sensor out-of-range due to heat/moisture stress
Control PCB sensor input fault

CH66Outdoor

Outdoor BLDC fan motor lock / fan fault

Typical causes

Outdoor fan motor lock or rotor resistance
Fan driver output fault on outdoor PCB
Physical obstruction or severe coil heat load

CH67Outdoor

BLDC fan motor lock protection

Typical causes

BLDC fan motor lock or startup failure
Fan motor feedback (Hall) signal abnormal
Outdoor PCB fan-drive circuit fault

CH90System

Test-run protection error (installation/piping/power related)

Typical causes

Installation test-run detected piping/refrigerant abnormality
Compressor load protection triggered during commissioning
Temporary power instability during startup

CH91System

Test-run protection error (installation/piping/power related)

Typical causes

Installation test-run detected piping/refrigerant abnormality
Compressor load protection triggered during commissioning
Temporary power instability during startup

CH93Communication

Indoor-outdoor communication instability

Typical causes

Indoor-outdoor communication line instability
Outdoor unit not receiving power on newer split-power models
Wiring/connector fault or communication PCB issue

F1General

Indoor floor-standing model system fault (F1)

Typical causes

Model-specific protection or control logic detected abnormal operation
Internal wiring or component fault
Control PCB requires professional diagnosis

F2General

Indoor floor-standing model system fault (F2)

Typical causes

Model-specific protection or control logic detected abnormal operation
Internal wiring or component fault
Control PCB requires professional diagnosis

F3General

Indoor floor-standing model system fault (F3)

Typical causes

Model-specific protection or control logic detected abnormal operation
Internal wiring or component fault
Control PCB requires professional diagnosis

FLIndoor

Condensate tank full / float-level protection

Typical causes

Condensate tank reached full level in high-humidity operation
Drain outlet blocked or drain cap not fitted correctly
Float or level-sensing circuit issue

P2Sensor

Room temperature sensing/control abnormality

Typical causes

Thermistor or sensor open/short circuit
Loose sensor connector or damaged harness
Sensor out-of-range due to heat/moisture stress
Control PCB sensor input fault

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