LG Multi V Systems: How the Codes Read
LG Multi V systems report a fault as a CH code (CH05, CH21) on the wired remote controller and the indoor unit. On the outdoor unit seven-segment display the same fault shows as a number with a trailing frame digit: 211 is CH21 on the master frame, and the 100-series codes are the sub outdoor frames reporting the same faults.
The number band tells you where to look, and getting it right is half the diagnosis. CH01 to CH11 is the indoor side and communication. CH21 to CH49 is the inverter, compressor and outdoor sensors. CH51 to CH67 is configuration, communication and protection. The 100-series is the multi-outdoor frames and the 200-series is heat-recovery boxes and central controllers.
This guide covers the LG Multi V VRF CH codes from the LG Electronics Australia fault-code sheet. Every code below is the sheet's own meaning. Residential split and Multi F codes are a different system and are out of scope here.
Communication Faults
The codes you will see most often on Multi V callouts. LG runs a two-wire transmission bus between indoor units, outdoor frames and controllers, and most of these come back to wiring, addressing or a PCB. CH05 shows at the indoor unit and CH53 at the outdoor unit for the same indoor-to-outdoor link.
Know about CH05 before the tenant does.
A Nexus controller sits on the system's control network and logs every fault the moment it happens: the code, the unit address, and the time. It lands in the AirNexus app before anyone calls you.
Indoor Unit Faults
Indoor sensor and actuator faults. These are a quick diagnosis: the sheet gives the expected sensor resistance, so measure at the connector, check the wiring, then replace the part.
Compressor and Inverter Faults
The codes that make your stomach drop. These sit on the inverter and compressor, the most expensive parts in the outdoor unit. Not every one means a compressor: the sheet's first checks are the compressor windings, insulation to earth, run current and the inverter DC link. Discharge the DC bus and verify before any connector work.
Pressure and Temperature Faults
High and low pressure trips and discharge-temperature protection. The sheet gives the trip thresholds (35 bar high, 1 bar low, 105C discharge), which is the first thing to confirm against the sensor reading.
Power and Protection Faults
Supply, phase, fan and configuration faults. The prefix and the outdoor frame digit matter here: the same fault on a sub outdoor frame shows as a 100-series number.
Tired of chasing CH codes?
Nexus iQ monitors discharge temperature, pressures, compressor current and communication health 24/7. It catches the patterns that lead to fault codes before they trip.
See How It WorksWhat Monitoring Catches That Fault Codes Miss
CH codes are reactive. By the time one appears, the fault has already happened. Every Multi V system generates dozens of parameters that change continuously: discharge temperature, high and low pressure, compressor current, and communication health. In a healthy system these hold consistent relationships. When something starts to degrade, a slow leak, a fouling coil, a transmission line picking up noise, the relationships shift long before any single parameter crosses a protection threshold.
Nexus iQ captures this data continuously and compares each system against its own history. When the patterns diverge you get a diagnostic insight, not a lockout.
| Scenario | Without Monitoring | With Nexus iQ |
|---|---|---|
| Slow refrigerant leak | CH35 low pressure trip on the coldest morning. Emergency callout. | Low-pressure trend flagged weeks earlier. Leak found during scheduled service. |
| Condenser fouling | CH34 high pressure trip on the hottest day. | High-pressure trend rising. Coil clean scheduled before summer peak. |
| Compressor stress building | CH21 DC-peak trip. Compressor replacement risk. | Current-to-frequency trend flagged months earlier. Planned repair. |
| Communication intermittent | Random CH05 / CH53 faults. Multiple callouts, no pattern found. | Transmission dropouts logged with timestamps. Pattern identified on the first visit. |
| Discharge temperature climbing | CH32 discharge-temperature protection stop. | Discharge trend against frequency flagged. Charge checked before the stop. |
The most expensive CH code is the one that trips on a Friday afternoon in January. Monitoring does not prevent failures, it prevents surprises.
Quick Reference: Every LG Multi V Code
Use this searchable table to find any Multi V code. Type a code (e.g. CH21), a keyword (e.g. sensor), or a category. Click any code to jump to its detail where one is provided above. The 100-series and 200-series are the outdoor-display numbers for the multi-frame and controller faults.
| Code | Category | Description | Severity |
|---|---|---|---|
| 100 | Multi-outdoor | Sub-unit standard compressor discharge temperature too high (over 105C) | High |
| 104 | Multi-outdoor | Communication error between main and sub outdoor units | Medium |
| 105 | Multi-outdoor | Communication error between outdoor main PCB and fan PCB | Medium |
| 106 | Multi-outdoor | Outdoor fan motor high current | High |
| 107 | Multi-outdoor | Low voltage to the fan PCB (300 V DC supply) | High |
| 109 | Multi-outdoor | Sub unit high pressure too high | High |
| 110 | Multi-outdoor | Sub unit reverse or open phase | High |
| 113 | Multi-outdoor | Main unit liquid pipe, subcool inlet and subcool outlet sensor faults | Medium |
| 116 | Multi-outdoor | Sub 1 sensor faults (HP, LP, air, suction, discharge 1 and 2, coil A and B, liquid, subcool in and out) | Medium |
| 128 | Multi-outdoor | Sub 2 sensor faults (same order as Sub 1) | Medium |
| 143 | Multi-outdoor | Sub 1 and Sub 2 high pressure too high or low pressure too low | High |
| 147 | Multi-outdoor | Sub 1 and Sub 2 supply voltage abnormal | High |
| 151 | Multi-outdoor | Four-way valve fault | High |
| 152 | Multi-outdoor | Sub condenser 2 standard compressor discharge temperature too high (over 105C) | High |
| 157 | Multi-outdoor | Sub 3 sensor faults (same order as Sub 1) | Medium |
| 169 | Multi-outdoor | Sub 3 high pressure too high or low pressure too low | High |
| 171 | Multi-outdoor | Sub 3 supply voltage abnormal | High |
| 173 | Multi-outdoor | Standard compressor not starting (main, sub 1 comp 1 and 2, sub 2 comp 1 and 2) | High |
| 204 | Controller | Communication error between outdoor unit and HR box 1, 2 or 3 | Medium |
| 240 | Controller | Central controller wiring error | Medium |
| 242 | Controller | Central controller data receiving error or time-out | Medium |
| 243 | Controller | Central controller communication cable too long or picking up noise | Medium |
| 245 | Controller | Central controller data sending time-out | Medium |
| 250 | Controller | Central controller receiving error, no data, incorrect address, or no response from air conditioner | Medium |
| CH01 | Indoor | Indoor return air sensor open or short | Medium |
| CH02 | Indoor | Indoor pipe sensor (or outdoor sensor assembly) open or short | Medium |
| CH03 | Communication | Wired remote controller communication error | Medium |
| CH04 | Indoor | Condensate pump float switch risen (commercial product) | Medium |
| CH05 | Communication | Communication error, indoor to outdoor | Medium |
| CH06 | Indoor | Indoor coil sensor fault | Medium |
| CH07 | Indoor | Indoor unit set to a different mode from the master indoor unit | Medium |
| CH09 | Indoor | Indoor unit EEPROM error (Multi V) | Medium |
| CH10 | Indoor | Indoor BLDC fan locked | High |
| CH11 | Communication | Indoor unit not connected to an outdoor unit (Multi V) | Medium |
| CH21 | Inverter | Inverter compressor run current high (DC peak) | Critical |
| CH22 | Inverter | Inverter compressor run current high (CT2, maximum current) | Critical |
| CH23 | Inverter | Inverter DC link voltage low | High |
| CH24 | Pressure/temp | High pressure trip (Multi V) | High |
| CH25 | Power | Outdoor supply voltage abnormal | High |
| CH26 | Inverter | Inverter compressor seized | Critical |
| CH27 | Inverter | Inverter current irregularity (PSC / reactor) | High |
| CH28 | Inverter | Inverter DC link voltage high | High |
| CH32 | Pressure/temp | Inverter compressor discharge temperature too high (over 105C) | High |
| CH33 | Pressure/temp | Standard compressor discharge temperature too high (over 105C) | High |
| CH34 | Pressure/temp | High pressure too high (over 35 bar at the HP sensor) | High |
| CH35 | Pressure/temp | Low pressure too low (under 1 bar at the LP sensor) | High |
| CH40 | Inverter | Inverter AC current abnormal | High |
| CH41 | Sensor | Inverter compressor discharge sensor fault | Medium |
| CH42 | Sensor | Low pressure sensor fault | Medium |
| CH43 | Sensor | High pressure sensor fault | Medium |
| CH44 | Sensor | Outdoor air sensor fault | Medium |
| CH45 | Sensor | Outdoor coil sensor fault | Medium |
| CH46 | Sensor | Outdoor suction sensor fault | Medium |
| CH47 | Sensor | Standard compressor discharge sensor fault | Medium |
| CH48 | Sensor | Outdoor coil sensor (Multi V) | Medium |
| CH49 | Power | Outdoor supply voltage abnormal | High |
| CH51 | Configuration | Unit mismatch, connected capacity exceeds the maximum | Medium |
| CH52 | Communication | Communication error, inverter PCB to outdoor main PCB | Medium |
| CH53 | Communication | Communication error, indoor units to outdoor unit | Medium |
| CH54 | Power | Reverse or open phase | High |
| CH57 | Communication | Communication error, outdoor main PCB to inverter PCB | Medium |
| CH60 | Configuration | Outdoor PCB EEPROM failure | Medium |
| CH61 | Pressure/temp | Condenser coil temperature over 65C | High |
| CH62 | Inverter | Inverter heatsink over 85C | High |
| CH65 | Sensor | Inverter heatsink temperature sensor fault | Medium |
| CH67 | Fan | Outdoor fan motor seized or rotation sensing failure | High |
Getting Started
Knowing what a CH code means is step one. Preventing it is step two. Here is how to move from reactive to predictive maintenance on your Multi V systems.
1. Book a Demo
See Nexus iQ monitoring a live Multi V system: real fault history, real diagnostic charts, real trending data on a real building. No slides, no hypotheticals.
2. Connect Your System
A Nexus controller connects directly to the LG Multi V communication bus. It reads every data point the system generates, temperatures, pressures, currents, frequencies, error codes and runtime hours, and streams it to the Nexus iQ cloud platform in real time.
3. Stop Guessing
Within 24 hours you have a complete diagnostic view of every outdoor and indoor unit. Within two weeks the platform has enough baseline data to flag anomalies. Within a month you receive predictive insights, the subtle pattern shifts no fault code would ever catch.
Sources
The code meanings in this guide are drawn from the following LG service document.
LG Multi V fault codes: frequently asked questions
What does LG error code CH05 mean?
CH05 is a communication error between the indoor and outdoor units, shown at the indoor unit. Check the transmission wiring; on Multi V you should read about 4 V DC across terminals 3 and 4, and remove any external condensate pumps wired into the circuit.
What is the difference between LG CH05 and CH53?
They are the same indoor-to-outdoor communication fault seen from two ends: CH05 is displayed at the indoor unit and CH53 at the outdoor unit. Check the transmission wiring and addressing between the units.
Can I monitor LG Multi V fault codes remotely?
Yes. The AirNexus Nexus iQ platform connects to LG Multi V systems and shows the fault in Findings & Insights and the Diagnostics view when the unit reports it, so you can see what is wrong before anyone goes to site. The AirNexus app also sends a push notification when a fault happens. Search the fault code lookup.