Perth's LG fault code lookup
LG fault codes decoded
66 codes covered — what each one means, the likely cause, and whether it's worth trying something yourself before booking. Compiled from LG documentation.
LG reports faults as CH-codes (CH01, CH05, CH21…) on the indoor unit display or wired controller — some models show the number alone without the CH prefix. The number tells you where to look: the low numbers are indoor-side, the twenties and thirties cover the compressor and inverter, the forties are outdoor sensors, and the fifties upward are system and communication faults.
How to find your LG fault code
Wall splits and multi-splits
- 1 LG shows a CH-code (CH01, CH05, CH21…) on the indoor unit's display or on the wired controller.
- 2 Some models display the number alone without the CH prefix, and a few show a two-character equivalent (CH05 appears as E0 on those).
- 3 The number tells you where to look: 01–12 indoor, 21–33 compressor and inverter, 40–48 outdoor sensors, 51–73 system and communication.
Before you look it up
- 1 Check the code isn't one of the display messages that aren't faults — those are listed in their own section below.
- 2 Switch off at the breaker for two minutes and restart. One-off trips clear; a code that returns is a genuine fault.
LG fault code tables
Indoor unit faults (CH01–CH12) — shown on the fascia display, wired controller, or as 1–12 LED flashes
| Code | What it means | Likely cause | What to do |
|---|---|---|---|
| CH01 | The indoor unit's room air (return air) temperature sensor has failed — it reads open circuit or short circuit, so the unit no longer knows the room temperature. | Failed thermistor, or a sensor plug that has worked loose from the indoor circuit board. On LG splits this sensor should read roughly 13 kOhm at 20C and 8 kOhm at 30C. | Book a service |
| CH02 | The indoor coil inlet pipe sensor has failed (open or short circuit). | Failed pipe thermistor or a loose/incorrectly seated connector at the indoor PCB. Typical reading is about 10 kOhm at 25C. | Book a service |
| CH03 | The indoor unit has lost communication with its wired wall controller. | Damaged or loose controller cable, a controller set to the wrong single/group address, a failed wall controller, or a failed indoor PCB. Common on ducted and cassette systems shortly after installation or after wall work. | Book a service |
| CH04 | Drainage fault — condensate is not being removed from the indoor unit and the float switch has tripped on a high water level. On some residential wall-split boards the same number instead reports a heat-sink sensor fault. | Blocked or badly graded condensate drain, failed condensate pump, a float switch stuck up, or (on ducted/cassette units with no pump fitted) a missing bridging link in the float connector. On window and portable units, high humidity simply filling the internal condensate tank. | Try this first Check the outdoor end of the drain line for a blockage, wasp nest or kink, and clear it. On a window or portable unit, switch off, unplug, put a 1.5 L pan under the drain port on the lower rear, remove the cap and let the water out, then refit the cap firmly. Then power cycle at the breaker for 5 minutes. If CH04/FL comes back on dry days, book service. |
| CH05 | Indoor–outdoor communication error, reported at the indoor unit. On models with a two-character display this shows as E0. | Damaged or loose interconnecting control wiring, a supply problem at the outdoor unit, or a failed PCB. CH53 is the paired annunciation shown at the other end. | Try this first Turn the air conditioner off at the circuit breaker (both indoor and outdoor breakers if separate), wait a full 5 minutes, then switch them back on together. This clears the fault in a large share of cases. If it returns, or it started right after installation or relocation, call the installer. |
| CH06 | The indoor coil outlet pipe sensor has failed (open or short circuit). | Failed outlet pipe thermistor or a loose plug at the indoor board. The unit shuts down because it can no longer protect the coil from freezing or overheating. | Book a service |
| CH07 | Different operating modes requested — one indoor head is set to a mode the system can't deliver at the same time as the others (multi-split systems). | Two heads set to conflicting modes, e.g. one heating while another cools. Set all heads to the same mode. | Try this first Walk around and check every indoor head on the system, including any you rarely use, and set them all to heating, or all to cooling/dehumidify. The code clears itself once the modes agree. |
| CH08 | Indoor BLDC fan motor problem — the indoor fan is locked and not rotating, so the indoor unit shuts down. Displayed as C8 on older Artcool/wall-mounted fascias. | Fan blade fouled or obstructed, bearing seizure, fan motor plug loose or damaged, failed fan motor, or no drive voltage from the indoor PCB (LG spec: roughly 120 V AC at low speed rising to ~170 V AC at high speed — voltage present means the motor is faulty, no voltage means the PCB is faulty). | Book a service |
| CH09 | Indoor unit memory (EEPROM) checksum fault — the control board cannot read its own settings data. | Defective indoor PCB, a corrupted or poorly seated EEPROM chip, or a communication failure between the processor and its memory. Documented on some ducted variants as an IPM sub-board fault instead. | Book a service |
| CH10 | The indoor fan motor is locked — the board commanded the fan to run but got no rotation feedback for about 50 seconds. Displays as E6 on some models. | Something jamming the indoor fan (debris, a fallen filter, a bird or vermin nest in a ducted unit), a failed BLDC fan motor, a disconnected motor plug, or a failed indoor PCB. | Try this first Switch off at the breaker first. Remove the filters and look and listen for anything obstructing the indoor fan barrel — leaves, a foreign object or built-up lint — and clear what you can safely reach. Restore power after 5 minutes. If it returns, the motor or board needs replacing. |
| CH11 | Indoor unit not connected to / not recognised by an outdoor unit — addressing or initialisation failure. Common on residential multi-head systems. | Incorrect or damaged communication wiring between the head and the outdoor unit, an indoor unit added or swapped without re-running auto-addressing, or initialisation not completed after installation. | Book a service |
| CH12 | The indoor mid-pipe (middle of coil) temperature sensor has failed (open or short circuit). | Failed mid-pipe thermistor, incorrect termination at the indoor PCB, or a failed board. As a rule, a sensor reading over 100 kOhm (open) or near zero (short) triggers this code. | Book a service |
Compressor and inverter power faults (CH21–CH33) — outdoor unit, generally switch off and call
| Code | What it means | Likely cause | What to do |
|---|---|---|---|
| CH13 | PSC (reactor) error on room air conditioner (RAC) products — the power-factor-correction reactor circuit has failed. Displayed as CD on older fascias. Closely related to CH27. | Open, shorted or disconnected reactor (should read well under 1 ohm), loose reactor connections at the outdoor PCB, or a failed inverter/main PCB. | Book a service |
| CH14 | Compressor phase current error on RAC products — the inverter has detected an abnormal or unbalanced current on one compressor phase. Displayed as CE on older fascias. | Unequal compressor winding resistances (should be within 1–4 ohms and equal across all three), winding-to-earth insulation breakdown (below ~50 Mohm), loose or corroded compressor terminals, or a failed inverter PCB output stage. | Book a service |
| CH21 | DC peak / IPM fault — the inverter power module detected an instantaneous overcurrent to the compressor and shut the system down to protect itself. | Failing compressor or shorted compressor windings, a failed IPM/inverter power board, abnormally high operating pressures, a stalled outdoor fan, or incorrect pipe length/refrigerant charge. | Switch off & call |
| CH22 | CT2 maximum current error — the input current to the outdoor unit has exceeded its safe limit (roughly 14 A, or 19–29 A on larger units). | Compressor drawing excessive current, a restricted or blocked refrigerant circuit, a dirty indoor filter or condenser coil forcing the system to overwork, low supply voltage, or an outdoor fan not running. | Switch off & call |
| CH23 | DC link voltage out of range. On legacy split and multi platforms this is DC link below roughly 140 V DC; on current R32 units it covers both low and high DC link conditions. | Supply voltage problems, a failed inverter PCB, or a faulty DC link capacitor. | Switch off & call |
| CH24 | The high- or low-pressure protection switch has opened — the refrigerant circuit is operating outside safe pressures. | Refrigerant overcharge or a blocked circuit, a failed indoor or outdoor fan motor, a restricted expansion valve, a closed service valve, badly restricted airflow over the coil, or a faulty pressure switch itself. | Switch off & call |
| CH25 | Abnormal AC supply voltage at the outdoor unit — the PCB has measured incoming voltage outside its safe window (documented as roughly below 140 V or above 300 V AC). | Genuine supply problems (brownout, loose neutral, overloaded circuit) or a faulty voltage-detection circuit on the outdoor PCB. | Switch off & call |
| CH26 | DC compressor position error — the inverter compressor failed to start or is not rotating properly. | Seized or mechanically failed compressor, incorrect or loose compressor U/V/W wiring, or a failed inverter drive board. | Switch off & call |
| CH27 | PSC fault — the outdoor board has detected abnormal current between the AC and DC sides of the inverter compressor circuit. | Inverter PCB fault, compressor winding problem, or wiring fault at the compressor. (Power-factor correction faults are the separate code CH73.) | Switch off & call |
| CH28 | DC link high voltage — the inverter's internal DC bus voltage has risen above its safe maximum. | Excessive incoming mains voltage, a faulty reactor or bridge diode, or a failed inverter board. | Switch off & call |
| CH29 | Inverter compressor input or phase current too high. | LG lists: refrigerant leak, compressor winding open or short, compressor insulation failure, or an inverter PCB fault. Thresholds vary by platform. | Switch off & call |
| CH31 | Current transformer (CT) current too low — the outdoor PCB is not sensing the expected running current. Listed by LG for single-zone wall-mounted residential systems (LSN/LSU HSV series). | Compressor not drawing current (not starting), CT sensor open or unplugged from the outdoor PCB, wiring fault in the CT circuit, or failed main PCB. | Book a service |
| CH32 | Inverter compressor discharge pipe temperature too high — the hot gas leaving the compressor has exceeded roughly 105C. | Refrigerant shortage or a leak, a defective electronic expansion valve, a blocked circuit, or a faulty discharge pipe sensor. Running on in this state damages the compressor. | Switch off & call |
| CH33 | Discharge pipe temperature high on a constant-speed (second) compressor — legacy multi and commercial tandem-compressor systems only, not residential single splits. | Low refrigerant charge or a failed discharge thermistor on the constant-speed compressor. | Switch off & call |
Outdoor sensor and current-detection faults (CH40–CH48)
| Code | What it means | Likely cause | What to do |
|---|---|---|---|
| CH40 | Current transformer (CT) circuit fault — the outdoor board cannot correctly measure compressor current. | Failed CT sensor on the inverter PCB, a blown fuse, a defective noise filter, or a bad phase connection. Current dropping below about 2 A while the compressor runs will trigger it. | Book a service |
| CH41 | The inverter compressor discharge pipe temperature sensor has failed (open or short circuit). | Failed discharge thermistor or a loose connector at the outdoor PCB. This is a high-temperature sensor — it should read around 200 kOhm at 25C, not the 10 kOhm of a normal pipe sensor. | Book a service |
| CH42 | Low-pressure sensor fault — the outdoor PCB is reading an open, shorted or out-of-range signal from the low-side pressure transducer. | Sensor unplugged, damaged loom or corroded plug, or a failed transducer. Diagnostic check is DC voltage between the white and black wires at the plug (reference scale: 1 V DC ≈ 4 bar up to 5 V DC ≈ 32 bar). | Book a service |
| CH43 | High-pressure sensor fault — open, shorted or out-of-range signal from the high-side pressure transducer. | Sensor unplugged, damaged loom or corroded plug, or a failed transducer. Diagnostic check is DC voltage between the white and black wires at the plug (reference scale: 1 V DC ≈ 8 bar up to 2.5 V DC ≈ 37 bar). | Book a service |
| CH44 | The outdoor unit's ambient (inlet) air temperature sensor has failed (open or short circuit). | Failed outdoor air thermistor, a loose plug at the outdoor PCB, or a failed board. Sensor should read about 13 kOhm at 20C and 8 kOhm at 30C. | Book a service |
| CH45 | The outdoor condenser coil (mid-pipe) temperature sensor has failed (open or short circuit). | Failed condenser pipe thermistor or a loose connector. Without it the unit cannot manage defrost or condensing temperature. | Book a service |
| CH46 | The outdoor suction line temperature sensor has failed (open or short circuit). | Failed suction pipe thermistor, poor connection at the outdoor PCB, or a failed board. | Book a service |
| CH47 | Constant-speed (second) compressor discharge pipe sensor open or short — applies to multi and commercial systems with a second compressor, not residential single splits. | Failed or disconnected discharge thermistor on the constant-speed compressor. | Book a service |
| CH48 | Both the discharge pipe sensor and the outdoor air sensor read open at once — usually the dual sensor plug is unplugged. | A dual sensor connector left off or knocked off the outdoor PCB, commonly after service work, or a damaged sensor harness. | Book a service |
| CH49 | Outdoor unit power-supply abnormality — supply voltage outside tolerance, or a blown outdoor fuse. Sits alongside CH25, which is already covered. | Incoming supply out of range (single-phase nominal 220–240 V AC ±10%, three-phase 380–415 V AC ±10%), tripped or failing breaker/isolator, blown fuse on the outdoor main PCB, loose supply terminations, or a failed outdoor main PCB. | Switch off & call |
System, communication, phase and protection faults (CH51–CH73, CH105)
| Code | What it means | Likely cause | What to do |
|---|---|---|---|
| CH51 | Over-capacity or mismatched combination — the connected indoor/outdoor pairing isn't valid. | LG's listed causes: indoor/outdoor mis-wiring, the wrong EEPROM applied to the indoor or outdoor PCB, or genuinely too much indoor capacity connected to the outdoor unit. | Book a service |
| CH52 | Communication failure between the outdoor unit's main control board and its inverter board. | Blown fuse on the main outdoor board, a loose ribbon or plug between the two boards, or a failed main or inverter PCB. | Book a service |
| CH53 | Indoor–outdoor communication error — the paired annunciation to CH05, reported from the other end of the link. | Same family of causes as CH05: interconnecting wiring, supply problems or PCB failure. Which unit displays the code tells the technician where to start. | Try this first Power the system down at the circuit breaker for a full 5 minutes, then restore it. If the code appeared immediately after installation or relocation, skip the reset and go straight back to the installer — it is almost certainly a wiring fault. |
| CH54 | Reverse phase or missing phase on a three-phase outdoor unit — the supply phases are in the wrong order or one has been lost. | Incorrect phase connection at installation, a lost phase after utility work or a power outage, or a tripped/failed supply protective device. Common immediately after electrical work on the switchboard. | Book a service |
| CH57 | Communication error between the outdoor main PCB and the inverter PCB — the two outdoor boards have lost their internal data link. Distinct from CH52, which LG lists in the opposite direction. | Loose or damaged inter-board harness, blown fuse on either board, board LEDs not lit indicating loss of supply to one board, or a defective inverter or main PCB. | Book a service |
| CH60 | Outdoor unit PCB memory (EEPROM) checksum error — the outdoor board cannot read its stored configuration. | A poorly seated or corrupted EEPROM chip, or a failed outdoor main PCB. | Book a service |
| CH61 | Overheating protection. In cooling, the outdoor condenser coil has exceeded roughly 65C. In heating, the indoor unit itself is running too hot. May appear as CH34, P4, P6, P7 or P8 depending on model. | In cooling: hot air recirculating around a boxed-in outdoor unit, clutter blocking airflow, or a dirty condenser coil. In heating: a clogged or dirty indoor filter starving the unit of air. Can also indicate high pressure from overcharge or non-condensables. | Try this first Clear at least 30 cm of open space around the outdoor unit and remove anything stacked against or over it; if it sits in an enclosed balcony or courtyard, open the vent window or screen. If the code came up in heating, pull out and wash the indoor filters. CH61 will not clear itself — after fixing the airflow you must power cycle at the breaker for 5 minutes. |
| CH62 | The inverter board's heat sink temperature is too high (over roughly 85C). | Failed heat-sink cooling fan or a loose fan connector, poor thermal contact between the inverter module and heat sink, a blocked or dirty heat sink, or a failed heat-sink temperature sensor. | Book a service |
| CH63 | Condenser coil pipe temperature too low — the outdoor coil is running colder than it should. | Refrigerant shortage, a faulty condenser pipe sensor giving a false reading, or restricted refrigerant flow. | Book a service |
| CH65 | The inverter heat sink temperature sensor has failed (open or short circuit). | Loose sensor connector, a failed heat-sink thermistor, or a failed inverter PCB. | Book a service |
| CH67 | The outdoor fan motor is locked — the board is getting no rotation feedback from the outdoor BLDC fan. Displays as EF on some models. | Debris jamming the outdoor fan blade, a seized or failed fan motor, a disconnected motor plug, or a failed outdoor PCB. | Try this first Switch off at the breaker, then clear leaves, sticks, plastic bags or garden growth from the outdoor fan grille and the space around the unit. Never put fingers or tools through the grille with power on. Restore power after 5 minutes; if the code returns, the fan motor needs replacing. |
| CH73 | Power factor correction (PFC) fault — the inverter board saw an input current spike above about 48 A. | A failing inverter or PFC circuit, a compressor drawing abnormal current, or a supply abnormality. | Switch off & call |
| CH105 | Communication failure between the outdoor main board and the outdoor fan control board. | Loose or damaged plug connections between the boards, or a failed main or fan PCB. | Book a service |
Newer residential models (approx. 2021 onward) and refrigerant/test-run codes
| Code | What it means | Likely cause | What to do |
|---|---|---|---|
| CH34 | Overheat protection in heating mode — the indoor unit's internal temperature is too high. A model-specific variant of CH61, also shown as P4, P6, P7 or P8. | Poor air intake at the indoor unit, most often a clogged or dirty air filter, or furniture and curtains blocking the return air path. | Try this first Take out the indoor filters, wash them in lukewarm water, dry them fully and refit. Make sure nothing is blocking the indoor unit's air intake or outlet. Then power cycle at the breaker for 5 minutes to clear the code. |
| CH35 | Excessive low-pressure drop — pressure has fallen below approximately 1 bar (15 psig) at the low-pressure sensor and the unit has tripped to protect the compressor. One of the most common real-world refrigerant-loss trips and a notable gap given CH34 (high pressure) is already covered. | Refrigerant leak or significant undercharge, service valves not fully opened after installation, blocked or restricted outdoor coil / restricted airflow, blocked filter drier or restricted metering device, faulty low-pressure sensor, or a defective PCB. | Book a service |
| CH38 | Low refrigerant — the system has detected a gas shortage and has protected itself by shutting down. Displays as F4 on some models. | A refrigerant leak somewhere in the pipework, flare joints or coils, or an undercharged system after installation or relocation. Running the unit in this state risks destroying the compressor. | Switch off & call |
| CH66 | A problem with the communication line or the pipework connection between the indoor and outdoor units, detected by inverter models. | Interconnecting cable or piping not correctly connected — most often seen straight after a new installation or a relocation. Can also be triggered temporarily by an unstable power supply. | Try this first If the system has been running fine and this appeared out of nowhere, switch off at the breaker for about 5 minutes and restore power. If it appeared right after installation or relocation, do not keep resetting it — contact the installer, as the piping or comms connections need checking. |
| CH90 | Test-run protection code, normally raised during commissioning to prevent damage to the appliance. Shown as F4 on some models. | Incorrect or incomplete piping connections detected during the test run, or a temporary electrical disturbance during normal operation. | Book a service |
| CH91 | Test-run protection code, paired with CH90 and displayed for the same protective reason. Shown as F4 on some models. | Piping connection problems found during commissioning, or a transient fault caused by unstable power. | Book a service |
| CH93 | Communication problem between the indoor and outdoor units, typically raised during the test run. On models released after 2021 it also appears when the outdoor unit is simply not receiving power. | Unstable communication during commissioning, or — on post-2021 models where indoor and outdoor units have separate power supplies — an unpowered outdoor unit, an unplugged power cord or a tripped outdoor breaker. | Try this first Check that the outdoor unit actually has power: confirm its plug is firmly in the wall outlet and its circuit breaker is on. Then power cycle both units at the breaker for 5 minutes. If the breaker will not stay on, stop and call a technician — do not keep resetting it. |
| CH237 | The outdoor unit has lost its power connection. Applies to post-2021 models where the indoor and outdoor units each have their own power cord and both must be powered. | Outdoor unit power plug pulled out or not fully seated, an overloaded or failed power board/power strip, or the outdoor circuit breaker switched off. | Try this first Plug the outdoor unit's power cord directly into a wall outlet — never a power strip or piggyback adaptor, which can be overloaded by the air conditioner. Then check the air conditioner's breaker is switched on. If the breaker will not reset, stop and book service. |
| CH238 | Outdoor unit power disconnected — the companion code to CH237 on post-2021 separately powered models. | Same as CH237: an unplugged or loose outdoor power connection, a shared/overloaded outlet, or a breaker that has been switched off or tripped. | Try this first Reseat the outdoor unit's plug directly into its own wall outlet and switch the air conditioner's breaker back on. If the breaker trips again immediately, leave it off and call a technician — repeated resetting of a tripping breaker is not safe. |
| E6 | Alias code for an indoor fan fault on newer residential models, equivalent to CH10 on those models. Customers searching the raw display text will not find it under a CH code. | Indoor fan blade obstructed or fouled, seized fan motor, loose motor plug, or failed indoor PCB. | Book a service |
| EF | Alias code for an outdoor fan fault on newer residential models, equivalent to CH67. | Outdoor fan blade obstructed by leaves or debris, seized outdoor fan motor, damaged motor wiring, or failed outdoor PCB fan-drive circuit. | Book a service |
| F4 | Alias code shown on some newer residential fascias and the LG ThinQ app for low refrigerant (gas) — the same condition as CH38, and also used for test-run piping-connection faults alongside CH90/CH91. | Refrigerant leak, undercharge, or service valves not opened after installation; on a new install, incorrect or restricted pipe connections found during test run. | Book a service |
Display messages that are NOT faults
| Code | What it means | Likely cause | What to do |
|---|---|---|---|
| CL | Child Lock is active — the controls are deliberately locked, not broken. | The lock has been switched on, often accidentally by someone pressing two buttons together. | Try this first Hold the Timer button and the minute / temperature-down button together for about 3 to 5 seconds to toggle Child Lock off. The display returns to normal straight away. |
| EO | On some LG models 'EO' on the indoor display is not an error at all — it indicates the kW Manager energy-limiting function is operating. Do not confuse it with E0, the alias for the CH05 communication fault. | kW Manager (power-limit) mode has been enabled. A genuine E0/CH05 communication fault will normally be accompanied by the indoor indicator light blinking at about 2-second intervals and the unit not running. | Try this first If the unit is otherwise heating or cooling normally, leave it alone — it is a status message. If the unit has stopped and the indicator is blinking, treat it as CH05 and power cycle at the breaker for 5 minutes. |
| HL | Hard Lock — the unit is being held off or restricted by an external source rather than by its own controls. | A dry-contact input (such as a key-card, window switch or building management signal) or a central controller is holding the unit in an off/disabled state, or that interface has failed. | Book a service |
| Lo | Test mode / test-run mode is active — a normal diagnostic display, not a fault. Belongs with CL, Po and HL in the not-a-fault section. | Unit left in test mode after installation or servicing, or test mode triggered inadvertently from the remote or wired controller. | Try this first |
| Po | Jet Cool (turbo cooling) mode is running — a normal operating indication. | Jet Cool has been selected on the remote, so the unit runs at maximum output for a set period. | Try this first Press the Jet Cool button again, or simply change the fan speed or set temperature, and the unit returns to normal operation. |
No matching code found.
Meanings vary by series and some codes are model-specific — call 0434 951 341 with the code and your model number and we'll decode it.
Reference compiled from LG service and operation documentation. Codes and meanings are provided as general guidance for the Australian residential range and can differ between model series; no affiliation with LG is implied.
Tell us the code when you book — diagnosis starts before we arrive
Fault finding across Perth from $165 inc GST — all brands, splits and ducted. Quoting the fault code gives us a head start on where to look; we then test and confirm the actual fault on site before any part is ordered, so you never pay for a part you didn't need.
Frequently Asked Questions
My LG shows a number without CH in front — same thing?
Yes. Some LG models display the bare number (05 rather than CH05) and a few older two-character displays show an E-prefixed equivalent — CH05 appears as E0 on those. Look up the number either way.
What's the difference between CH05 and CH53?
They're the two ends of the same problem: an indoor–outdoor communication failure. Which one you see depends on which unit is doing the reporting, and that's genuinely useful to a technician because it narrows down where the break is.
Is my LG code definitely in this list?
A few CH-codes in LG's wider documentation only apply to systems with a second, constant-speed compressor — CH33 and CH47 among them — which means multi and commercial equipment rather than a residential split. If your code isn't here, call 0434 951 341 with your model number.
The display says Lo or CL — is that a fault?
No. Those are status messages, not faults, and they're listed in their own section below so you can stop worrying about them.
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