When your LG system stops and shows a code, that code is the system telling you roughly where the problem is. Roughly is the key word. A fault code points in a direction, it rarely names the exact fix. Find your system below, tap your code, and it will take you straight to what it means and what to do.
Before you try anything: the only DIY steps that are ever safe are switching the system off at the isolator (and waiting 20 to 30 minutes), cleaning or checking filters, checking the controller settings and batteries, and keeping the outdoor unit clear. Anything behind a panel, anything electrical, and anything involving refrigerant or gas is licensed work. If a code below says switch off and call, please take it at its word.
How to read the tables: 🟢 means there is a safe first step worth trying. 🟡 means book a service, the system needs a technician. 🔴 means switch the system off at the isolator and call us on (02) 4760 0100.
Residential splits (RAC) – CH codes
Where the code shows: Shown as CHxx on the indoor unit display or wired remote controller. Some models show only the number, or a short C-form (C1-C9, CA, CC, Cd, CE)..
Tap your code: CH01CH02CH03CH04CH05CH06CH07CH08CH09CH10CH12CH21CH22CH23CH24CH25CH26CH27CH28CH32CH33CH34CH35CH40CH41CH42CH43CH44CH45CH46CH47CH48CH49CH51CH52CH53CH54CH57CH60CH61CH62CH65CH67C1C2C4C5C6C7C8C9CACCCdCECLPoHL
| Code | What it means | What to do |
|---|---|---|
| CH01 | The indoor unit's return-air temperature sensor isn't reading properly. Indoor return air sensor open/short. |
🟡 Book a service call – this one needs a technician. |
| CH02 | The indoor pipe sensor or the outdoor sensor assembly isn't reading properly. Indoor pipe sensor / outdoor sensor assembly open or short. |
🟡 Book a service call – this one needs a technician. |
| CH03 | The wired remote controller has lost communication with the indoor unit. Remote controller comms error – wiring or controller dip-switch setting (Sg for single unit, Gr for group). |
🟢 Turn the system off at the isolator, wait 20-30 minutes, then turn it back on. If the code returns, book a service. |
| CH04 | The temperature sensor on the outdoor electronics heatsink is faulty or has overheated. On residential (RAC) units: heat-sink sensor open/short or over 95 degrees C. On commercial indoor units this code means the drain float switch has risen – see the ducted/cassette list. |
🟡 Book a service call – this one needs a technician. |
| CH05 | The indoor and outdoor units have stopped talking to each other. Indoor-outdoor communication error. |
🟢 Turn the system off at the isolator, wait 20-30 minutes, then turn it back on. If the code returns, book a service. |
| CH06 | The indoor coil's temperature sensor isn't reading properly. Indoor coil sensor fault. |
🟡 Book a service call – this one needs a technician. |
| CH07 | The compressor drew too much current and the unit shut down. (On multi-head systems this same code means an indoor-unit mode conflict instead – see the multi-split list.) Single splits: compressor over-current (CT2). |
🔴 Turn the system off at the isolator and call us – don't keep running it. |
| CH08 | The indoor fan motor is jammed or not spinning. Indoor BLDC fan locked / fan motor or fan PCB fault. |
🟡 Book a service call – this one needs a technician. |
| CH09 | The outdoor fan motor isn't running properly. Outdoor fan motor or outdoor PCB fault (single splits). |
🟡 Check nothing is blocking the outdoor unit, then book a service if the fault stays. |
| CH10 | The compressor discharge temperature sensor isn't reading properly. Compressor discharge sensor fault (residential units). On Multi F(DX) and Multi V this code points to the indoor fan fault instead. |
🟡 Book a service call – this one needs a technician. |
| CH12 | The temperature sensor on the middle of the indoor unit's coil isn't reading properly. Indoor middle-pipe thermistor open/short (the companion coil sensors are CH02 pipe-inlet and CH06 pipe-outlet). The keyword list called 12 an 'EEPROM sum check error', but no other LG source agrees and the list's own CH12 entry disowns the code – corrected to LG's documented meaning. |
🟡 Book a service call – this one needs a technician. |
| CH21 | The inverter compressor is drawing too much current. Inverter compressor run current high (DC peak). The source gives CH21 and CH22 identical wording. |
🔴 Turn the system off at the isolator and call us – don't keep running it. |
| CH22 | The inverter compressor is drawing too much current. Inverter compressor run current high (max current). The source gives CH21 and CH22 identical wording. |
🔴 Turn the system off at the isolator and call us – don't keep running it. |
| CH23 | The voltage inside the outdoor unit's inverter has dropped too low. Inverter DC voltage low – often follows a power dip or brownout. |
🟢 Turn the system off at the isolator, wait 20-30 minutes, then turn it back on. If the code returns, book a service. |
| CH24 | The system tripped on refrigerant pressure – too high or too low. High/low pressure trip (low ~1 bar, high ~35 bar) on splits and multi splits. |
🔴 Turn the system off at the isolator and call us – don't keep running it. |
| CH25 | The incoming power supply voltage is outside the unit's safe range. Input voltage error (230 V single-phase / 400 V three-phase, +/-10%). |
🟢 Turn the system off at the isolator, wait 20-30 minutes, then turn it back on. If the code returns, book a service. |
| CH26 | The inverter compressor has seized or won't turn. Inverter compressor seized / locked rotor. |
🔴 Turn the system off at the isolator and call us – don't keep running it. |
| CH27 | The inverter is measuring irregular electrical current. Inverter current irregularity – inverter PCB or reactor. |
🟡 Book a service call – this one needs a technician. |
| CH28 | The voltage inside the outdoor unit's inverter has risen too high. Inverter DC voltage too high – often follows a power surge. |
🟢 Turn the system off at the isolator, wait 20-30 minutes, then turn it back on. If the code returns, book a service. |
| CH32 | The inverter compressor got too hot and the unit shut down to prevent damage. Inverter compressor discharge temperature over ~105 degrees C – can point to low refrigerant. |
🔴 Turn the system off at the isolator and call us. Refrigerant work needs a licensed technician. |
| CH33 | The standard compressor got too hot and the unit shut down to prevent damage. Standard compressor discharge temperature over ~105 degrees C – can point to low refrigerant. |
🔴 Turn the system off at the isolator and call us. Refrigerant work needs a licensed technician. |
| CH34 | Refrigerant pressure climbed far too high and the unit shut down to protect itself. High-pressure trip over ~35 bar – blocked coils, dirty filters or non-condensables in the pipework. |
🔴 Turn the system off at the isolator and call us – don't keep running it. |
| CH35 | Refrigerant pressure dropped far too low and the unit shut down to protect itself. Low-pressure trip under ~1 bar – can point to refrigerant loss or closed service valves. |
🔴 Turn the system off at the isolator and call us. Refrigerant work needs a licensed technician. |
| CH40 | The inverter is measuring abnormal AC current to the compressor. Inverter AC current abnormal (CT sensor circuit). |
🔴 Turn the system off at the isolator and call us – don't keep running it. |
| CH41 | The inverter compressor's discharge temperature sensor isn't reading properly. Inverter compressor discharge sensor fault. |
🟡 Book a service call – this one needs a technician. |
| CH42 | The low-pressure sensor isn't reading properly. Low pressure sensor fault. |
🟡 Book a service call – this one needs a technician. |
| CH43 | The high-pressure sensor isn't reading properly. High pressure sensor fault. |
🟡 Book a service call – this one needs a technician. |
| CH44 | The outdoor air temperature sensor isn't reading properly. Outdoor air sensor fault. |
🟡 Book a service call – this one needs a technician. |
| CH45 | The outdoor coil temperature sensor isn't reading properly. Outdoor coil sensor fault. |
🟡 Book a service call – this one needs a technician. |
| CH46 | The outdoor unit's suction temperature sensor isn't reading properly. Outdoor suction sensor fault. |
🟡 Book a service call – this one needs a technician. |
| CH47 | The compressor discharge temperature sensor isn't reading properly. Compressor discharge sensor fault. |
🟡 Book a service call – this one needs a technician. |
| CH48 | Two outdoor sensors (discharge and air) are both unplugged or not reading. Outdoor discharge and air sensors both open (splits/multi splits). On Multi V this code means the outdoor coil sensor instead. |
🟡 Book a service call – this one needs a technician. |
| CH49 | The incoming power supply voltage is outside the unit's safe range. Input voltage error (230 V single-phase / 400 V three-phase, +/-10%). |
🟢 Turn the system off at the isolator, wait 20-30 minutes, then turn it back on. If the code returns, book a service. |
| CH51 | The connected indoor units add up to more capacity than the outdoor unit allows. Unit capacity mismatch / over-combination. |
🟡 Book a service call – this one needs a technician. |
| CH52 | The outdoor unit's two circuit boards (main and inverter) have lost communication with each other. Main PCB to inverter PCB communication error. |
🟢 Turn the system off at the isolator, wait 20-30 minutes, then turn it back on. If the code returns, book a service. |
| CH53 | The indoor and outdoor units have stopped talking to each other. Indoor to outdoor communication error. |
🟢 Turn the system off at the isolator, wait 20-30 minutes, then turn it back on. If the code returns, book a service. |
| CH54 | The three-phase power supply has a phase missing or connected in the wrong order. Reverse or open phase (three-phase models) – needs an electrician or technician. |
🟡 Book a service call – this one needs a technician. |
| CH57 | The outdoor unit's two circuit boards (main and inverter) have lost communication with each other. Main PCB to inverter PCB communication error. |
🟢 Turn the system off at the isolator, wait 20-30 minutes, then turn it back on. If the code returns, book a service. |
| CH60 | The outdoor unit's control board has a memory (EEPROM) fault. Outdoor PCB EEPROM failure. |
🟡 Book a service call – this one needs a technician. |
| CH61 | The outdoor coil got too hot – usually blocked airflow or a dirty coil. Condenser coil temperature over ~65 degrees C. |
🟡 Check nothing is blocking the outdoor unit and clear leaves or debris away from it, then book a service if the code returns. |
| CH62 | The outdoor unit's inverter electronics overheated and the unit shut down to protect itself. Inverter heatsink over ~85 degrees C. |
🔴 Turn the system off at the isolator and call us – don't keep running it. |
| CH65 | The temperature sensor on the inverter heatsink isn't reading properly. Inverter fin temperature sensor fault. |
🟡 Book a service call – this one needs a technician. |
| CH67 | The outdoor fan motor has seized or its rotation can't be detected. Outdoor fan motor locked / rotation-sensing failure. |
🟡 Check nothing is blocking the outdoor unit, then book a service if the fault stays. |
| C1 | The indoor unit's return-air temperature sensor isn't reading properly. Short display form of CH01. |
🟡 Book a service call – this one needs a technician. |
| C2 | The indoor pipe sensor or the outdoor sensor assembly isn't reading properly. Short display form of CH02. |
🟡 Book a service call – this one needs a technician. |
| C4 | The heatsink temperature sensor is faulty or has overheated (residential units). Short display form of CH04. On commercial indoor units this code means the drain float switch has risen. |
🟡 Book a service call – this one needs a technician. |
| C5 | The indoor and outdoor units have stopped talking to each other. Short display form of CH05. |
🟢 Turn the system off at the isolator, wait 20-30 minutes, then turn it back on. If the code returns, book a service. |
| C6 | The inverter compressor is drawing too much current. NOTE: the source lists C6 as compressor run-current high (the CH21/22 fault), NOT the CH06 coil-sensor fault – do not read C6 as CH06. |
🔴 Turn the system off at the isolator and call us – don't keep running it. |
| C7 | The compressor drew too much current and the unit shut down. Compressor over-current (CT2) – short form of the splits meaning of CH07. |
🔴 Turn the system off at the isolator and call us – don't keep running it. |
| C8 | The indoor fan motor is jammed or not spinning. Short display form of CH08. |
🟡 Book a service call – this one needs a technician. |
| C9 | The outdoor fan motor isn't running properly. Short display form of CH09. |
🟡 Check nothing is blocking the outdoor unit, then book a service if the fault stays. |
| CA | The compressor discharge temperature sensor isn't reading properly. Hex-style short form of code 10 (discharge sensor fault). |
🟡 Book a service call – this one needs a technician. |
| CC | The outdoor control board has a memory (EEPROM) fault. Hex-style short form of code 12 (EEPROM sum-check error). |
🟡 Book a service call – this one needs a technician. |
| Cd | The unit's power-factor circuit (PSC/reactor) has a fault. Hex-style short form of code 13 (PSC/reactor error). |
🟡 Book a service call – this one needs a technician. |
| CE | The compressor is drawing abnormal current on one of its phases. Hex-style short form of code 14 (compressor phase current error). |
🔴 Turn the system off at the isolator and call us – don't keep running it. |
| CL | Child lock is switched on – this is a setting, not a fault. Child lock display. |
🟢 Press the Timer and Min buttons together for 5 seconds to turn child lock off. |
| Po | The unit is running in Jet Cool (power cool) mode – this is a setting, not a fault. Jet Cool mode display. |
🟢 Press the Jet Cool, Fan Speed or Set Temperature button to return to normal operation. |
| HL | The condensate drain safety switch has risen – the drain pan or pump needs attention. Float switch risen (units with a drain pump). Can also mean an attached Dry Contact interface is set to OFF. |
🟡 Book a service call – the drain needs attention before it can run safely. |
Multi split / Multi F(DX) – codes whose meaning differs from the single-split list
Where the code shows: Shown as CHxx on the indoor unit display or wired remote controller. Codes not listed here read the same as the residential split list..
| Code | What it means | What to do |
|---|---|---|
| CH05 | The indoor and outdoor units have stopped talking to each other. Indoor-outdoor communication error. |
🟢 Turn the system off at the isolator, wait 20-30 minutes, then turn it back on. If the code returns, book a service. |
| CH07 | One indoor unit is set to a different mode from the others – a multi system can only heat or cool, not both at once. Indoor unit mode conflict with the master indoor unit. |
🟢 Set every indoor unit to the same mode (all cooling or all heating), then try again. If the code stays, book a service. |
| CH10 | An indoor fan motor is jammed or not spinning. On Multi F(DX) code 10 refers to the indoor BLDC fan fault (the code-08 fault on splits). |
🟡 Book a service call – this one needs a technician. |
| CH24 | The system tripped on refrigerant pressure – too high or too low. High/low pressure trip (low ~1 bar, high ~35 bar). |
🔴 Turn the system off at the isolator and call us – don't keep running it. |
| CH51 | The connected indoor units add up to more capacity than the outdoor unit allows. Unit capacity mismatch / over-combination. |
🟡 Book a service call – this one needs a technician. |
| CH63 | The outdoor coil pipe sensor is reading abnormally cold. Multi F(DX) only: condenser pipe temperature low (the opposite condition to code 61). |
🟡 Book a service call – this one needs a technician. |
Multi V (VRF) – including multi-outdoor sub units and heat-recovery boxes
Where the code shows: Shown as CHxx on indoor units/wired controllers; outdoor-module (sub unit) codes 100+ display on the outdoor unit PCB. Codes not listed here read the same as the residential split list..
Tap your code: CH05CH07CH09CH10CH11CH24CH42CH43CH48CH51CH62CH104CH105CH106CH107CH108CH109CH110CH111CH113CH114CH115CH116CH117CH118CH120CH121CH122CH123CH124CH125CH126CH127CH128CH129CH130CH132CH133CH134CH135CH136CH137CH138CH139CH140CH141CH142CH144CH146CH151CH154CH155CH156CH157CH158CH159CH161CH162CH163CH164CH165CH166CH167CH168CH170CH173CH174CH175CH176CH177CH204CH208CH212
| Code | What it means | What to do |
|---|---|---|
| CH05 | The indoor and outdoor units have stopped talking to each other. Indoor-outdoor communication error (Multi V comms bus). |
🟢 Turn the system off at the isolator, wait 20-30 minutes, then turn it back on. If the code returns, book a service. |
| CH07 | One indoor unit is set to a different mode from the others – the system can only heat or cool, not both at once (unless fitted with heat-recovery boxes). Indoor unit mode conflict with the master indoor unit. |
🟢 Set every indoor unit to the same mode (all cooling or all heating), then try again. If the code stays, book a service. |
| CH09 | An indoor unit's control board has a memory (EEPROM) fault. Multi V: indoor EEPROM error – board replacement plus re-addressing. |
🟡 Book a service call – this one needs a technician. |
| CH10 | An indoor fan motor is jammed or not spinning. Multi V: code 10 refers to the indoor BLDC fan fault. |
🟡 Book a service call – this one needs a technician. |
| CH11 | An indoor unit isn't registered with the outdoor unit. Indoor unit not connected / not initialised on the comms bus. |
🟡 Book a service call – this one needs a technician. |
| CH24 | The system shut down because refrigerant pressure climbed too high. Multi V: high pressure trip. |
🔴 Turn the system off at the isolator and call us – don't keep running it. |
| CH42 | The low-pressure sensor isn't reading properly. Low pressure sensor fault. |
🟡 Book a service call – this one needs a technician. |
| CH43 | The high-pressure sensor isn't reading properly. High pressure sensor fault. |
🟡 Book a service call – this one needs a technician. |
| CH48 | The outdoor coil temperature sensor isn't reading properly. Multi V meaning of code 48 (on splits it means two sensors unplugged). |
🟡 Book a service call – this one needs a technician. |
| CH51 | The connected indoor units add up to more capacity than the outdoor units allow, or a sub outdoor unit is set up incorrectly. Over-combination / sub outdoor unit dip-switch settings. |
🟡 Book a service call – this one needs a technician. |
| CH62 | The inverter electronics overheated and the unit shut down to protect itself. Inverter heatsink over ~85 degrees C; Multi V also has an inverter cooling fan that can fail. |
🔴 Turn the system off at the isolator and call us – don't keep running it. |
| CH104 | The main and sub outdoor units have stopped talking to each other. Main-sub outdoor unit communication error. |
🟢 Turn the system off at the isolator, wait 20-30 minutes, then turn it back on. If the code returns, book a service. |
| CH105 | Two boards inside the outdoor unit (main PCB and fan PCB) have lost communication. Main PCB to fan PCB communication error. |
🟢 Turn the system off at the isolator, wait 20-30 minutes, then turn it back on. If the code returns, book a service. |
| CH106 | An outdoor fan motor is drawing too much current. Outdoor fan motor high current. |
🟡 Check nothing is blocking the outdoor unit, then book a service if the fault stays. |
| CH107 | The outdoor fan control board isn't getting enough voltage. Low DC voltage to fan PCB. |
🟡 Book a service call – this one needs a technician. |
| CH108 | Two boards inside the outdoor unit (main PCB and fan PCB) have lost communication. Main PCB to fan PCB communication error (duplicate of 105 in the source). |
🟢 Turn the system off at the isolator, wait 20-30 minutes, then turn it back on. If the code returns, book a service. |
| CH109 | Refrigerant pressure climbed too high on this outdoor module and it shut down to protect itself. Sub 1 excessive high-pressure rise. |
🔴 Turn the system off at the isolator and call us – don't keep running it. |
| CH110 | This outdoor module's three-phase power supply has a phase missing or connected in the wrong order. Sub 1 reverse or open phase. |
🟡 Book a service call – this one needs a technician. |
| CH111 | The main and sub outdoor units have stopped talking to each other. Main-sub outdoor unit communication error. |
🟢 Turn the system off at the isolator, wait 20-30 minutes, then turn it back on. If the code returns, book a service. |
| CH113 | The main outdoor unit's liquid pipe sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH114 | The main outdoor unit's subcool inlet sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH115 | The main outdoor unit's subcool outlet sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH116 | The sub 1 outdoor unit's high-pressure sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH117 | The sub 1 outdoor unit's low-pressure sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH118 | The sub 1 outdoor unit's air temperature sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH120 | The sub 1 outdoor unit's suction temperature sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH121 | The sub 1 unit's compressor 1 discharge sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH122 | The sub 1 unit's compressor 2 discharge sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH123 | The sub 1 outdoor unit's coil sensor A isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH124 | The sub 1 outdoor unit's coil sensor B isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH125 | The sub 1 outdoor unit's liquid pipe sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH126 | The sub 1 outdoor unit's subcool inlet sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH127 | The sub 1 outdoor unit's subcool outlet sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH128 | The sub 2 outdoor unit's high-pressure sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH129 | The sub 2 outdoor unit's low-pressure sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH130 | The sub 2 outdoor unit's air temperature sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH132 | The sub 2 outdoor unit's suction temperature sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH133 | The sub 2 unit's compressor 1 discharge sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH134 | The sub 2 unit's compressor 2 discharge sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH135 | The sub 2 outdoor unit's coil sensor A isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH136 | The sub 2 outdoor unit's coil sensor B isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH137 | The sub 2 outdoor unit's liquid pipe sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH138 | The sub 2 outdoor unit's subcool inlet sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH139 | The sub 2 outdoor unit's subcool outlet sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH140 | Refrigerant pressure climbed too high on this outdoor module and it shut down to protect itself. Sub 2 excessive high-pressure rise. |
🔴 Turn the system off at the isolator and call us – don't keep running it. |
| CH141 | This outdoor module's three-phase power supply has a phase missing or connected in the wrong order. Sub 2 reverse or open phase. |
🟡 Book a service call – this one needs a technician. |
| CH142 | The main and sub outdoor units have stopped talking to each other. Main-sub outdoor unit communication error. |
🟢 Turn the system off at the isolator, wait 20-30 minutes, then turn it back on. If the code returns, book a service. |
| CH144 | Refrigerant pressure dropped too low on this outdoor module and it shut down to protect itself. Sub 1 excessive low-pressure drop. |
🔴 Turn the system off at the isolator and call us. Refrigerant work needs a licensed technician. |
| CH146 | Refrigerant pressure dropped too low on this outdoor module and it shut down to protect itself. Sub 2 excessive low-pressure drop. |
🔴 Turn the system off at the isolator and call us. Refrigerant work needs a licensed technician. |
| CH151 | The valve that switches the system between heating and cooling has failed. Faulty 4-way (reversing) valve. |
🟡 Book a service call – this one needs a technician. |
| CH154 | Refrigerant pressure climbed too high on this outdoor module and it shut down to protect itself. Sub 3 excessive high-pressure rise. |
🔴 Turn the system off at the isolator and call us – don't keep running it. |
| CH155 | This outdoor module's three-phase power supply has a phase missing or connected in the wrong order. Sub 3 reverse or open phase. |
🟡 Book a service call – this one needs a technician. |
| CH156 | The main and sub outdoor units have stopped talking to each other. Main-sub outdoor unit communication error. |
🟢 Turn the system off at the isolator, wait 20-30 minutes, then turn it back on. If the code returns, book a service. |
| CH157 | The sub 3 outdoor unit's high-pressure sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH158 | The sub 3 outdoor unit's low-pressure sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH159 | The sub 3 outdoor unit's air temperature sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH161 | The sub 3 outdoor unit's suction temperature sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH162 | The sub 3 unit's compressor 1 discharge sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH163 | The sub 3 unit's compressor 2 discharge sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH164 | The sub 3 outdoor unit's coil sensor A isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH165 | The sub 3 outdoor unit's coil sensor B isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH166 | The sub 3 outdoor unit's liquid pipe sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH167 | The sub 3 outdoor unit's subcool inlet sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH168 | The sub 3 outdoor unit's subcool outlet sensor isn't reading properly. Sensor open/short – technician diagnosis. |
🟡 Book a service call – this one needs a technician. |
| CH170 | Refrigerant pressure dropped too low on this outdoor module and it shut down to protect itself. Sub 3 excessive low-pressure drop. |
🔴 Turn the system off at the isolator and call us. Refrigerant work needs a licensed technician. |
| CH173 | A compressor on the main outdoor unit is failing to start. Main unit standard compressor not starting – PCB output, contactor or compressor. |
🟡 Book a service call – this one needs a technician. |
| CH174 | A compressor on sub outdoor unit 1 is failing to start. Sub 1 standard compressor 1 not starting. |
🟡 Book a service call – this one needs a technician. |
| CH175 | A compressor on sub outdoor unit 1 is failing to start. Sub 1 standard compressor 2 not starting. |
🟡 Book a service call – this one needs a technician. |
| CH176 | A compressor on sub outdoor unit 2 is failing to start. Sub 2 standard compressor 1 not starting. |
🟡 Book a service call – this one needs a technician. |
| CH177 | A compressor on sub outdoor unit 2 is failing to start. Sub 2 standard compressor 2 not starting. |
🟡 Book a service call – this one needs a technician. |
| CH204 | The outdoor unit has lost communication with heat-recovery box 1. HR box 1 comms – power/transmission connections, rotary/dip switch settings, or HR unit PCB. |
🟡 Book a service call – this one needs a technician. |
| CH208 | The outdoor unit has lost communication with heat-recovery box 2. HR box 2 comms – power/transmission connections, rotary/dip switch settings, or HR unit PCB. |
🟡 Book a service call – this one needs a technician. |
| CH212 | The outdoor unit has lost communication with heat-recovery box 3. HR box 3 comms – power/transmission connections, rotary/dip switch settings, or HR unit PCB. |
🟡 Book a service call – this one needs a technician. |
Central controller / CNU (codes 240-253)
Where the code shows: Shown on the central controller..
| Code | What it means | What to do |
|---|---|---|
| 240 | The central controller's wiring isn't connecting it to the system properly. Central controller wiring error – comms wiring, CNU, IP addresses. |
🟡 Book a service call – this one needs a technician. |
| 241 | The central controller can't send data to the system. Data sending error – CNU or controller initialisation. |
🟡 Book a service call – this one needs a technician. |
| 242 | The central controller can't receive data from the system. Data receiving error – CNU or controller initialisation. |
🟡 Book a service call – this one needs a technician. |
| 243 | The central controller's communication line is too long or picking up electrical interference. Comms cable length / electrical noise, controller mismatch, or CNU. |
🟡 Book a service call – this one needs a technician. |
| 244 | The central controller timed out waiting to receive data. Data receiving time-out – CNU or controller initialisation. |
🟡 Book a service call – this one needs a technician. |
| 245 | The central controller timed out trying to send data. Data sending time-out – CNU or controller initialisation. |
🟡 Book a service call – this one needs a technician. |
| 246 | The central controller timed out waiting to receive data. Data receiving time-out (duplicate of 244 in the source). |
🟡 Book a service call – this one needs a technician. |
| 250 | The central controller is receiving corrupted data. Data receiving error – electrical noise on the comms cable or CNU. |
🟡 Book a service call – this one needs a technician. |
| 251 | The central controller is receiving no data at all. No data received – electrical noise on the comms cable or CNU. |
🟡 Book a service call – this one needs a technician. |
| 252 | The central controller's address settings don't match the system. Incorrect address error. |
🟡 Book a service call – this one needs a technician. |
| 253 | The central controller is getting no response from the air conditioner. Disconnection error – wiring, electrical noise, CNU or interface. |
🟡 Book a service call – this one needs a technician. |
Commercial indoor units (ducted/cassette) – codes whose meaning differs from the split list
Where the code shows: Shown as CHxx (or HL) on the wired remote controller. Codes not listed here read the same as the residential split list..
| Code | What it means | What to do |
|---|---|---|
| CH04 | The condensate drain safety switch has risen – the drain pan or pump needs attention. Commercial indoor units (ducted/cassette): condensate pump float switch risen. On residential wall splits this same code means a heatsink sensor fault instead. |
🟡 Book a service call – the drain needs attention before it can run safely. |
| HL | The condensate drain safety switch has risen – the drain pan or pump needs attention. Float switch risen. Can also mean an attached Dry Contact interface is set to OFF. |
🟡 Book a service call – the drain needs attention before it can run safely. |
Code still showing after a reset? Mention the code and your system type when you book and our office can line up the right technician and likely parts before we arrive.
Book a service or call (02) 4760 0100 (24-hour line, Penrith & Blue Mountains).
Codes vary between models and generations, and manufacturers revise them. This guide is compiled from official service documentation and checked by Ample Air, but it is general information, not a diagnosis. Refrigerant and electrical work must be carried out by licensed technicians. Ample Air, ARC licences AU12976 & AU15788. Last verified August 2026.