LG Multi V Error Code Guide: CH Codes Explained (Indoor, Outdoor, HR Units)
If your LG Multi V VRF system's outdoor unit is showing a 2-, 3-, or 4-digit number on its 7-segment display, or your LGMV controller or wired remote is showing a CH code, this guide decodes it. Codes are transcribed directly from LG's own service manuals and troubleshooting guides for the Multi V III, Multi V 5, and heat-recovery (ARUB/ARUN) product lines — nothing here is guessed.
How to read the code
On the outdoor unit's SSD (7-segment display), the code is usually shown as a 3- or 4-digit number. The rightmost digit identifies which outdoor unit frame is reporting the fault: 1 = Master, 2 = Slave 1, 3 = Slave 2, 4 = Slave 3 (on older multi-frame systems). The remaining digits are the error number itself. So 211 is error 21 on the Master unit, and 1051 is error 105 on the Master. In this guide, codes are written as the base 2–3 digit number the way LG's controllers label them ("CH" prefix) — where a code is followed by an asterisk (*) below, that means the frame digit gets appended in the field (e.g. CH21* becomes 211/212/213/214 depending on which unit is faulting).
Heat recovery (HR) unit errors are followed by the HR unit number, shown as "C" in the tables below (e.g. CH201C). If two or more errors occur at once, the lower-numbered code displays first; once that fault clears, the next one shows.
Response severity (Multi V 5): Level 4 just notifies you and keeps the system running; Level 3 shows the code and shuts the unit down for 3 minutes before auto-restarting (escalating to Level 1 after 10 occurrences in an hour); Level 2 covers communication errors specifically; Level 1 is an immediate shutdown that needs a manual power reset.
Indoor unit (IDU) error codes
| Code | What it means | Check these first |
|---|---|---|
| CH01 | Indoor unit return-air/wall temperature sensor open or shorted | Sensor connector at CN-ROOM; sensor should read ~10 kΩ at 25°C. If good, suspect the IDU PCB. |
| CH02 | Indoor unit inlet pipe temperature sensor open or shorted | Sensor at CN-PIPE1, ~5 kΩ at 25°C |
| CH03 | Wired remote controller isn't hearing from the indoor unit | Remote controller, IDU PCB, CN-REMO connector, and the transmission cable — check its run distance from power cabling (noise). Re-run auto addressing after any PCB swap. |
| CH04 | Drain overflow / drain pump fault | Float switch (should short at low water level, open when full), drain pump output (should read 220V), drain line routing/clogs |
| CH05 | Outdoor unit isn't hearing from this indoor unit (legacy IDUs) | Auto addressing completed?, comm cable connection/shorts, distance from power cabling |
| CH05 (Gen 4 IDUs) | Different meaning on Gen 4: lost communication between the IDU main PCB and its SUB PCB | IDU main PCB ↔ SUB PCB wiring |
| CH06 | Outlet pipe temperature sensor open or shorted (or hydro kit liquid-side sensor) | Sensor at CN-PIPE2 |
| CH07 | Indoor units are running in conflicting modes (heat pump systems) | Which IDUs are in heat vs. cool; PCB and remote controller |
| CH08 | Hydro kit hot water tank temperature sensor error | Tank sensor and its connections |
| CH09 | Indoor unit EEPROM communication error | Option-card seating on the IDU PCB; if replacing the PCB, redo auto addressing and central-control address afterward |
| CH10 | Indoor BLDC fan motor isn't reporting feedback (~50 sec) | Motor connector, wiring plug, Hall sensor (should read hundreds of kΩ) — also check nothing is left in the fan discharge shroud on new installs |
| CH11 (legacy) | IDU isn't hearing from the ODU main PCB for 3+ minutes | Indoor 485 transmission PCB; redo auto addressing after any PCB swap |
| CH11 (Multi V 5) | Hydro kit isn't hearing from the inverter compressor PCB | Hydro kit comm wiring/PCB |
| CH12–CH18 | Hydro kit sensor and communication faults (inverter PCB, solar/leaving-water sensors, flow switch, inlet/outlet pipe sensors) | See the specific sensor/switch named by the code; all are hydro-kit specific |
| CH230 | Refrigerant leak sensor tripped, or the sensor is faulty/missing while the leak-detect option is enabled (Gen 4 IDUs) | Sensor should read under 1.5V normally; a real leak trip closes the IDU-side solenoid and needs a power reset to clear |
| CH237 | Lost comm between the ODU's IDU-communication PCB and the IDU SUB PCB (Gen 4 IDUs) | RS-485 wiring |
| CH238 | Lost comm between the ODU's IDU-communication PCB and the ODU main PCB (Gen 4 IDUs) | ODU-side PCBs |
Outdoor unit (ODU) error codes
Frame digit gets appended in the field (21* → 211 Master / 212 Slave1 / 213 Slave2 / 214 Slave3).
| Code | What it means | Check these first |
|---|---|---|
| CH21 | Inverter compressor IPM fault (overcurrent on a compressor phase) | Overload (clogged/covered coil, bad EEV, overcharge), compressor winding/insulation, IPM heatsink fan, compressor terminal, inverter PCB |
| CH22 | Inverter PCB AC input overcurrent | Overload operation, compressor damage, low input voltage, power line connections, inverter PCB current-sensing circuit |
| CH23 | Inverter compressor DC link voltage out of range | DC-link terminal connections, starting relay, main capacitor, inverter PCB voltage-sensing circuit, input voltage |
| CH24 | High pressure switch tripped | Pressure switch, IDU/ODU fan operation, compressor check valve, pipe damage, refrigerant overcharge, EEV, airflow blockage, ODU PCB |
| CH25 | Input voltage out of range (high or low) | Line voltage at the disconnect vs. the unit's rated window; inverter PCB voltage-sensing circuit |
| CH26 | Inverter compressor failed to start | Overload, compressor winding/insulation, compressor wiring, inverter PCB CT circuit |
| CH28 | Inverter DC link voltage too high | Input voltage (R,S,T,N), inverter PCB voltage-sensing circuit |
| CH29 | Inverter compressor input overcurrent | Overload, compressor damage, low input voltage, inverter PCB; on Multi V 5 also check for refrigerant piping restriction |
| CH32 / CH33 | Compressor discharge temperature too high (comp 1 / comp 2) | Discharge temp sensor, refrigerant charge/leak, EEV, liquid injection valve |
| CH34 | High pressure sensor tripped 3 times in a row | High pressure sensor, fan operation, pipe damage, overcharge, EEV, airflow blockage, ODU PCB |
| CH35 | Low pressure sensor tripped 3 times in a row | Low pressure sensor, fan operation, refrigerant shortage/leak, pipe damage, EEV, airflow blockage, ODU PCB |
| CH36 | Compression ratio too low | 4-way (reversing) valve position, refrigerant charge, compressor lift |
| CH40 | Inverter compressor CT sensor error | Input voltage, inverter PCB CT sensing circuit |
| CH41 / CH47 | Compressor discharge pipe temperature sensor open/shorted (comp 1 / comp 2) | Sensor connection and continuity; on Multi V 5, can false-trigger in cooling at very low ambient without the low-ambient kit |
| CH42 | Low pressure sensor open/shorted | Connector, 12V/5V supply, signal-to-ground vs. LG's pressure chart |
| CH43 | High pressure sensor open/shorted | Same checks as CH42 |
| CH44 | Outdoor ambient temperature sensor open/shorted | Connector, sensor, ODU PCB |
| CH45 / CH46 | Heat exchanger or suction pipe temperature sensor open/shorted | Connector, sensor, ODU PCB |
| CH49 | IPM temperature sensor open/shorted | Sensor connection, ODU PCB |
| CH50 | Missing a 3-phase power leg (R/S/T) | Input voltage on all three legs, power line connections, main PCB, inverter PCB current sensor |
| CH51 | Connected indoor unit capacity is out of range for the outdoor unit (under ~50% or over ~130% of ODU rated capacity) | Total nominal IDU capacity vs. ODU spec; slave ODU DIP switches (Slave1: No.5,7; Slave2: No.6,7; Slave3: No.5,6,7) |
| CH52 | Inverter PCB isn't hearing from the main PCB | Connections at both PCB sockets; interconnecting cable condition |
| CH53 | Main PCB isn't hearing from an indoor unit | Comm cable connections/shorts, A/B terminal assignments, IDU count vs. LGMV |
| CH54 | 3-phase power wired wrong (reversed or missing a phase) | Main PCB, R/S/T wiring order, main PCB fuse |
| CH57 | Main PCB and inverter PCB can't hear each other | Connection between them, cable noise, both PCBs |
| CH59 | Wrong unit set as Master (smaller-capacity ODU set as Master instead of largest) | DIP switch settings — largest-capacity unit should be Master, ordered Master → Slave1 → Slave2 → Slave3 |
| CH60 | Inverter PCB EEPROM error | EEPROM seating/orientation (notch aligned to socket arrow), EEPROM version, inverter PCB |
| CH62 | Inverter heatsink over-temperature (>125°C) — system shuts off | IGBT/IPM connections, ODU fan motor, overload conditions (clogged pipe, blocked fan), inverter PCB |
| CH65 | LG's own manual disagrees with itself here. The summary table in the Multi V 5 service manual calls this "inverter heatsink temperature sensor error," while the detail page for the same code describes it as "outdoor unit liquid pipe (condenser) temperature sensor error." Both readings are confirmed present in the source document. Until LG clarifies which is correct for your unit, treat a CH65 code as a temperature-sensor fault and check both the inverter heatsink sensor and the liquid pipe sensor for open/short conditions before replacing either. | Sensor connections and resistance on both the inverter heatsink sensor and the liquid pipe sensor; ODU PCB |
| CH67 | Outdoor fan locked or not spinning | Fan motor and connector (Hall sensor, U/V/W wiring), fan PCB, snow/ice blocking the fan |
| CH71 | Same kind of manual conflict as CH65. The Multi V 5 detail page describes this as an outdoor unit "converter CT sensor error," while the summary table in the same manual lists it as "inverter CT sensor error / unit is restricted." (On legacy ARUN units, CH71 instead means a PFC CT sensor error.) Confirm which generation of unit you have before diagnosing, and check both the converter and inverter CT sensing circuits. | Input voltage (R-T), converter PCB CT sensing component, inverter PCB CT circuit |
| CH73 | AC input instant (peak) overcurrent | Overload, compressor damage, input voltage, power line assembly, inverter PCB current sensing |
| CH75 | Outdoor fan CT sensor error | Input voltage (should be 15V), fan PCB, power wiring, inverter PCB |
| CH76 | Outdoor fan DC link voltage too high | Input power, fan PCB, power wiring |
| CH77 | Outdoor fan overcurrent | Overload, fan motor, fan PCB, fan motor connector, iced/blocked coil |
| CH79 | Outdoor fan failed to start | Fan motor and connector (Hall sensor, U/V/W), fan PCB |
| CH86 / CH87 | Main PCB or fan PCB EEPROM error | EEPROM presence/seating, checksum, socket orientation |
| CH104 | Outdoor units can't hear each other | Power/comm cable connections between Master and Slave units, each unit's PCB, DIP switch settings from commissioning |
| CH105 | Fan PCB and inverter/main PCB can't hear each other | Wiring between them, fan PCB power supply, both PCBs |
| CH106 | Outdoor fan IPM fault | Overload, fan motor winding condition, fan PCB heatsink assembly |
| CH107 | Outdoor fan DC link voltage too low | Wiring between inverter and fan PCB, reactor and DC-link terminal contacts, bridge diode |
| CH113–CH115 | Liquid pipe / subcooling circuit temperature sensor errors | Sensor connection and resistance, ODU PCB |
| CH116 | Low oil level, or the oil level sensor itself is faulty | Oil level sensor and actual oil level |
| CH145 | Main board can't reach an external board | Board connections and external board |
| CH150 | Compressor discharge superheat too low for 5+ minutes (only in all-cooling operation) — risk of liquid floodback | Refrigerant charge, EEV operation, discharge temperature sensor |
| CH151 | Not enough pressure difference between high and low side / 4-way valve not switching properly | 4-way valve (coil resistance should be ~2,085Ω), sludge in the valve, compressor condition, common pipe installation |
| CH153 / CH154 | Upper/lower heat exchanger temperature sensor error | Sensor, thermistor, ODU PCB |
| CH182 | Main ↔ sub MICOM communication error on the ODU main board | Sub-MICOM LED status; try a reset before replacing the main PCB |
| CH187 | Hydro kit freeze-protection fault (inlet water too cold, or a water temp sensor error) | Water temperature sensors, glycol level, water flow — the hydro kit can't protect its heat exchanger from freezing if glycol is inadequate or the kit is powered off |
| CH193 / CH194 | Outdoor fan PCB heatsink over-temperature or its sensor error | Heatsink temp sensor, fan PCB |
Heat recovery unit and network/system codes
| Code | What it means | Check these first |
|---|---|---|
| CH51 C | Indoor unit capacity connected to a heat-recovery branch exceeds the limit (over ~54 MBh on a single port, ~108 MBh on two twinned ports, ~162 MBh on three grouped ports, or ~192 MBh total per HR unit) | HR port addressing and connected IDU capacity — verify roughly 5 minutes after auto-pipe detection finishes |
| CH200 | Auto pipe search couldn't find an indoor unit (detected count doesn't match communicating count) | Power/comm cable to the HR unit, IDU addressing after auto-addressing, HR unit's rotary/DIP switches |
| CH201 C – CH203 C | HR unit liquid pipe / subcooling pipe sensor errors | Sensor and connections, HR unit PCB |
| CH204 C | Outdoor unit isn't hearing from the heat recovery unit | Comm bus wiring, HR unit PCB |
| CH205 | Comm error between the HR unit and the 485 modem/bus (Gen 4: between the HR box main PCB and its Communication PCB) | HR unit's 485 modem or comm PCB, bus wiring |
| CH206 | Two heat recovery units are sharing the same address (Gen 4: duplicate rotary-dial addresses) | Adjust the HEX/rotary address dial on the affected HR units |
| CH242 | Central controller can't get information from the outdoor unit | RS-485 wiring, DIP switch settings, duplicate IDU addresses on the central controller |
Codes new to Gen 4 indoor units and HR boxes
If you're working on a newer Gen 4 IDU or HR box, LG's Service Technical Note STN-33 documents six codes that didn't exist on Gen 2 hardware: CH05 (now means IDU main PCB ↔ SUB PCB comm loss, instead of its older meaning), CH230 (refrigerant leak sensor), CH237 and CH238 (IDU/ODU communication-PCB chain errors), and CH205 / CH206 on the HR side (communication and duplicate-address errors). These are noted above alongside their legacy meanings where applicable.
What we can't confirm yet
Two things are worth flagging honestly rather than guessing at: first, CH65 and CH71 each have a genuine contradiction inside LG's own Multi V 5 service manual — the summary table and the detail page for each code describe different faults. We've listed both readings above rather than picking one. Second, the troubleshooting guide's own code index references detail pages for codes up to CH272 (including a CH201–CH246 range), but the edition we have access to stops at CH242 — so if your unit displays something in the CH243–CH272 range, we don't have a sourced explanation for it yet. If you're chasing a code that isn't listed here, or want a second opinion on a CH65/CH71 read, give us a call with the model and serial number and we'll help you track it down.
FDD self-test codes (not CH codes)
Multi V 5 systems also have an FDD (Fault Detection & Diagnosis) self-test mode that reports E01–E10 codes — these are separate from the CH codes above and only appear while running the FDD test:
| Code | Meaning |
|---|---|
| E01 | Connected indoor unit capacity is above 130% or below 80% of the outdoor unit's rated capacity |
| E02 | System is unstable |
| E03 | Temperature is outside the test's valid range |
| E04 | Can't run FDD while the unit is defrosting |
| E05 | Sensor check function error |
| E06 | Only one indoor unit is connected |
| E07 | Button wasn't pressed to start the auto refrigerant charge function |
| E08 | FDD was forced to terminate, or auto refrigerant charge completed normally |
| E09 | System is off / waiting to run FDD |
| E10 | System needs additional refrigerant |
Frequently Asked Questions
How do I read the frame digit in an LG Multi V outdoor unit error code?
On the outdoor unit's 7-segment display, the rightmost digit identifies which outdoor unit frame is reporting the fault: 1 = Master, 2 = Slave 1, 3 = Slave 2, 4 = Slave 3. The remaining digits are the error number itself — so 211 is error 21 on the Master, and 1051 is error 105 on the Master.
What does LG Multi V error code CH21 mean?
Inverter compressor IPM fault (overcurrent on a compressor phase). Check for overload conditions (clogged/covered coil, bad EEV, overcharge), compressor winding/insulation, the IPM heatsink fan, the compressor terminal, and the inverter PCB.
What are the response severity levels on a Multi V 5 system?
Level 4 just notifies you and keeps the system running; Level 3 shows the code and shuts the unit down for 3 minutes before auto-restarting (escalating to Level 1 after 10 occurrences in an hour); Level 2 covers communication errors specifically; Level 1 is an immediate shutdown that needs a manual power reset.
What does CH65 mean on an LG Multi V system?
LG's own Multi V 5 service manual disagrees with itself here — the summary table calls it an "inverter heatsink temperature sensor error," while the detail page for the same code describes it as an "outdoor unit liquid pipe (condenser) temperature sensor error." We list both readings rather than picking one; check both the inverter heatsink sensor and the liquid pipe sensor for open/short conditions before replacing either.
What does CH71 mean on an LG Multi V system?
Same kind of manual conflict as CH65: the Multi V 5 detail page calls it a "converter CT sensor error," while the summary table in the same manual lists it as an "inverter CT sensor error / unit is restricted." On legacy ARUN units, CH71 instead means a PFC CT sensor error. Confirm which generation of unit you have before diagnosing.
Are there LG Multi V error codes not covered in this guide?
Yes — LG's troubleshooting guide index references codes up to CH272, but the edition we have access to stops at CH242. If your unit displays something in the CH243–CH272 range, we don't have a sourced explanation for it yet. Call us with the model and serial number and we'll help track it down.
What are the E01–E10 codes on a Multi V 5 system?
These are FDD (Fault Detection & Diagnosis) self-test codes, separate from the CH fault codes, and only appear while running the FDD self-test — for example E01 means connected indoor unit capacity is above 130% or below 80% of the outdoor unit's rated capacity, and E10 means the system needs additional refrigerant.
Looking for LG VRF parts to fix what you've diagnosed — control boards, sensors, EEVs, or a full DFS system bundle? Browse our LGMV service tools and control modules or search your part number directly. For serial number and model decoding, see our LG Multi V serial number lookup.
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