HVAC Toolkit

LG Error Codes

Complete fault code reference for LG mini-splits and air conditioners

Quick Reference: CH = Main fault codes | PO = Protection/operating codes | C1-C5 = Cassette/ceiling units

CH Codes (Main Fault Codes)

Code Description Possible Cause Solution
CH01 Indoor unit return air thermistor fault Thermistor open, short, or out of range Check thermistor resistance (10kΩ at 25°C typical), replace if faulty
CH02 Indoor pipe (coil) thermistor fault Evaporator thermistor malfunction Check thermistor connection and resistance, replace if needed
CH03 Wired remote control communication error Communication wire fault or remote failure Check wiring connections, verify polarity, test remote
CH04 Drain pump error Drain pump failure or float switch activated Check pump operation, clear drain line, check float switch
CH05 Indoor/Outdoor communication error Communication wire issue between units Check 3-wire connection, verify polarity, check for loose wires
CH06 Outlet pipe thermistor fault Discharge thermistor malfunction Check and replace thermistor
CH07 Indoor unit BLDC fan motor error Fan motor locked, overload, or feedback error Check for obstruction, test motor, verify connections
CH09 Indoor unit EEPROM error Indoor PCB memory fault Reset power, replace PCB if error persists
CH10 Indoor unit BLDC motor IPM fault Inverter power module failure Check motor windings, replace indoor PCB
CH12 Indoor louver motor error Swing/louver motor stuck or limit fault Check motor operation, reset louver position
CH21 Outdoor unit DC peak current Compressor overcurrent protection Check refrigerant charge, compressor condition
CH22 Outdoor unit CT (current) sensor error Current transformer fault Check sensor connections, replace outdoor PCB
CH23 Outdoor DC link low voltage Low bus voltage on inverter Check power supply voltage, capacitors
CH24 Outdoor DC link high voltage High bus voltage on inverter Check power supply, input voltage
CH25 Outdoor unit AC over-voltage Input voltage too high Verify supply voltage is within spec
CH26 Compressor overcurrent (CT) Compressor drawing excessive current Check compressor, refrigerant charge, voltage
CH27 Outdoor unit PSC error Power switching circuit fault Check outdoor inverter board
CH29 Outdoor IPM (Inverter Power Module) fault Compressor inverter module failure Check compressor windings, replace outdoor PCB
CH32 Outdoor unit high pressure protection High head pressure detected Clean condenser, check refrigerant charge, verify fan operation
CH33 Outdoor unit low pressure protection Low suction pressure detected Check for leaks, verify refrigerant charge
CH34 Discharge temperature too high Compressor overheating Check charge, superheat, compressor condition
CH35 Discharge thermistor fault Compressor discharge sensor failure Check and replace thermistor
CH38 Outdoor ambient thermistor fault Ambient temperature sensor failure Check and replace outdoor thermistor
CH39 Condenser middle thermistor fault Mid-coil temperature sensor failure Check and replace thermistor
CH40 Condenser outlet thermistor fault Liquid line temperature sensor failure Check and replace thermistor
CH41 Low pressure sensor fault Pressure transducer failure Check sensor connections, replace if faulty
CH43 Suction thermistor fault Suction line temperature sensor failure Check and replace thermistor
CH44 Outdoor unit EEPROM error Outdoor PCB memory fault Reset power, replace outdoor PCB if persists
CH45 Outdoor unit fan motor error Outdoor fan motor locked or overcurrent Check for obstruction, test motor
CH46 Outdoor unit overheat protection PCB or heat sink overtemperature Check ventilation, clean PCB area
CH47 High pressure sensor fault Pressure transducer failure Check sensor connections, replace if faulty
CH53 Phase missing/reverse detection Power phase issue (3-phase units) Check all phases, verify phase sequence
CH60 Sub-compressor overcurrent Secondary compressor fault (dual compressor) Check sub-compressor windings and connections
CH61 Compressor position detection error Inverter cannot detect rotor position Check compressor and inverter board
CH62 Inverter module sensor fault Inverter temperature sensor failure Check sensor, replace outdoor PCB
CH65 Outdoor unit fan motor BLDC error DC fan motor fault Check motor and connections
CH67 Outdoor fan motor low speed Fan not reaching target RPM Check motor, capacitor, verify power

PO Codes (Protection/Operating Codes)

Code Description Possible Cause Solution
PO 01 High pressure cutout HP switch tripped Check refrigerant charge, condenser coil, fan operation
PO 02 Indoor anti-freeze protection Evaporator coil freezing detected Check airflow, filter, refrigerant charge
PO 04 Discharge pipe temperature protection Compressor overheating Check superheat, refrigerant charge
PO 05 Inverter IPM overheating Inverter module too hot Check ventilation around outdoor unit
PO 06 Compressor low frequency protection Compressor running at minimum limit Check load conditions, thermistor readings
PO 07 Compressor high frequency protection Compressor running at maximum limit Check load conditions, reduce demand
PO 09 Voltage protection Input voltage out of range Check and correct power supply voltage

C1-C5 Codes (Cassette/Ceiling Units)

Code Description Possible Cause Solution
C1 Ceiling panel thermistor fault Panel sensor failure Check and replace ceiling panel sensor
C2 Ceiling panel communication error Panel to PCB communication fault Check panel connections
C4 Panel condensation sensor fault Humidity/condensation sensor failure Check and replace sensor
C5 Panel filter clogged Auto-filter cleaning required Clean or replace air filter

LED Flash Codes

Code Description Possible Cause Solution
1 Flash Indoor/outdoor communication error No communication between units Check wiring, polarity, connections
2 Flashes Indoor coil thermistor fault Evaporator sensor failure Check and replace coil thermistor
3 Flashes Indoor room thermistor fault Room temperature sensor failure Check and replace room sensor
4 Flashes Outdoor coil thermistor fault Condenser sensor failure Check and replace outdoor coil sensor
5 Flashes Outdoor ambient thermistor fault Ambient sensor failure Check and replace ambient sensor
6 Flashes EEPROM fault PCB memory error Reset power, replace PCB if needed
7 Flashes Compressor overload Compressor protection activated Check compressor, charge, voltage
8 Flashes Fan motor fault Indoor or outdoor fan error Check both fan motors
9 Flashes Condenser high temperature Outdoor coil too hot Clean condenser, check airflow
10 Flashes Compressor overheating Discharge temperature high Check superheat, refrigerant charge

LG Error Code Troubleshooting Tips

Reading Error Codes

  • • Press and hold the Mode button for 5 seconds to enter diagnostic mode
  • • Error codes display on the indoor unit LED or remote
  • • Some units display codes when pressing the Test button
  • • Multi-split systems show which indoor unit has the fault

Common Solutions

  • • CH05: Most common - check communication wiring first
  • • CH10: Fan motor issue - check for obstruction
  • • CH32/33: Pressure issues - verify refrigerant charge
  • • Always power cycle unit after fixing the issue

Communication Wire Connections (CH05)

LG units use a 3-wire communication system. The wires connect to terminals labeled 1, 2, 3 (or S, C, N). Ensure all three wires are connected, matching the same terminals on indoor and outdoor units. Check for loose connections, damaged wire, or incorrect polarity.