What does your Daikin fault code mean?
Pick the code showing on your remote, wall controller or indoor unit and see what it means, what commonly causes it, and what is safe to check yourself. This page covers 87 Daikin fault codes for units sold in Australia, compiled from official Australian manufacturer and distributor documentation, the same references our own technicians carry.
Heads up: Daikin uses the same code with different meanings on different product ranges, so check the model range shown next to the code.
Every Daikin fault code at a glance
Some models show faults as a flashing-light pattern instead of a code; documented lamp patterns are listed alongside their codes.
| Code | What it means | Severity |
|---|---|---|
| 00 (Split, ducted, multi head and cassette systems (varies by series)) | No fault is stored and the system is reporting normal operation. | Normal operation |
| A0 (Split, ducted, multi head and cassette systems (varies by series)) | An external protection device connected to the unit has tripped and shut the system down. | Fault – service needed |
| A1 (Split, ducted, multi head and cassette systems (varies by series)) | The indoor unit’s main circuit board has failed or is not reading correctly. | Fault – service needed |
| A3 (Ducted, cassette and any unit fitted with a condensate pump) | The condensate drain system has failed, usually because water is not draining away. | Fault – service needed |
| A4 (Split, ducted, multi head and cassette systems (varies by series)) | The freeze protection function has activated because the indoor coil is getting too cold. | Minor fault |
| A5 (Split, ducted, multi head and cassette systems (varies by series)) | The unit has cut back or stopped to protect itself, from high pressure in heating or the coil freezing up in cooling. | Minor fault |
| A6 (Split, ducted, multi head and cassette systems (varies by series)) | The indoor fan motor has locked up, overloaded or drawn too much current. | Fault – service needed |
| A7 (Split, ducted, multi head and cassette systems (varies by series)) | The motor that moves the air swing louvre has failed. | Minor fault |
| A8 (Split, ducted, multi head and cassette systems (varies by series)) | The indoor unit has detected a power supply fault or too much current on its input. | Fault – service needed |
| A9 (Split, ducted, multi head and cassette systems (varies by series)) | The electronic expansion valve in the indoor unit is not working properly. | Fault – service needed |
| AA (Systems fitted with a heater, including some ducted units) | The heater inside the unit has overheated. | Fault – service needed |
| AF (Units fitted with a humidifier, and some ducted systems) | The humidifier system has a fault, often linked to water drainage. | Minor fault |
| AH (Split systems with Streamer air purification, and units with a dust collector) | The air purification unit, the Streamer or dust collector, has a fault. | Minor fault |
| AJ (Split, ducted, multi head and cassette systems (varies by series)) | The indoor unit’s capacity setting is wrong or missing, usually after a circuit board has been replaced. | Fault – service needed |
| C1 (Split, ducted, multi head and cassette systems (varies by series)) | Communication between the indoor circuit board and the fan motor has failed. | Fault – service needed |
| C4 (Split, ducted, multi head and cassette systems (varies by series)) | The temperature sensor on the indoor coil, the liquid pipe side, is faulty. | Minor fault |
| C5 (Split, ducted, multi head and cassette systems (varies by series)) | The temperature sensor on the indoor coil, the gas pipe side, is faulty. | Minor fault |
| C6 (Split, ducted, multi head and cassette systems (varies by series)) | The indoor fan motor’s speed sensor or drive circuit has a fault. | Fault – service needed |
| C7 (Split systems with a motorised front panel, such as Emura and Nexura) | The motor that opens and closes the front panel or louvre has a fault. | Minor fault |
| C9 (Split, ducted, multi head and cassette systems (varies by series)) | The sensor that reads the return air temperature is faulty. | Minor fault |
| CA (Split, ducted, multi head and cassette systems (varies by series)) | The sensor that reads the air temperature blowing out of the unit is faulty. | Minor fault |
| CC (Split systems with a humidity sensor, such as US7 and Zena) | The humidity sensor in the indoor unit is faulty. | Minor fault |
| CJ (Systems with a wired controller, mainly ducted and cassette) | The temperature sensor inside the wall controller is faulty, so the unit falls back to its own sensor. | Minor fault |
| E0 (Split, ducted, multi head and cassette systems (varies by series)) | A protection device in the outdoor unit has activated and shut the system down. | Fault – service needed |
| E1 (Split, ducted, multi head and cassette systems (varies by series)) | The outdoor unit’s main circuit board has failed. | Fault – service needed |
| E3 (Split, ducted, multi head and cassette systems (varies by series)) | The high pressure safety switch has tripped because pressure in the refrigerant circuit went too high. | Fault – service needed |
| E4 (Split, ducted, multi head and cassette systems (varies by series)) | The low pressure safety switch has tripped because pressure in the refrigerant circuit went too low. | Fault – service needed |
| E5 (Split, ducted, multi head and cassette systems (varies by series)) | The compressor motor has overloaded or locked up and the unit has shut down to protect it. | Fault – service needed |
| E6 (Split, ducted, multi head and cassette systems (varies by series)) | The compressor failed to start properly or drew too much current. | Fault – service needed |
| E7 (Split, ducted, multi head and cassette systems (varies by series)) | The outdoor fan motor has a fault and is not running properly. | Fault – service needed |
| E8 (Split, ducted, multi head and cassette systems (varies by series)) | The unit shut down because too much current was being drawn on the power input. | Fault – service needed |
| E9 (Split, ducted, multi head and cassette systems (varies by series)) | The electronic expansion valve in the outdoor unit is not working properly. | Fault – service needed |
| EA (Split, ducted, multi head and cassette systems (varies by series)) | The valve that switches the system between cooling and heating has a fault. | Fault – service needed |
| F3 (Split, ducted, multi head and cassette systems (varies by series)) | The pipe leaving the compressor got too hot and the unit shut down to protect itself. | Fault – service needed |
| F6 (Split, ducted, multi head and cassette systems (varies by series)) | Pressure in the refrigerant circuit went too high during cooling, often from a blocked outdoor coil or too much refrigerant. | Fault – service needed |
| H0 (Split, ducted, multi head and cassette systems (varies by series)) | A sensor in the compressor system is giving a bad reading. | Minor fault |
| H1 (Splits with a built in humidifier such as the Ururu Sarara (US7); on some other series H1 is an air temperature sensor fault) | The damper in the humidifier unit is not working properly, or on some models an air temperature sensor has failed. | Minor fault |
| H3 (Split, ducted, multi head and cassette systems (varies by series)) | The high pressure switch itself is faulty or wired incorrectly. | Minor fault |
| H4 (Split, ducted, multi head and cassette systems (varies by series)) | The low pressure switch itself is faulty or wired incorrectly. | Minor fault |
| H5 (Split, ducted, multi head and cassette systems (varies by series)) | The sensor that watches the compressor motor for overload is faulty. | Minor fault |
| H6 (Split, ducted, multi head and cassette systems (varies by series)) | The unit stopped because the sensor that tracks the compressor motor position gave a bad reading. | Fault – service needed |
| H7 (Split, ducted, multi head and cassette systems (varies by series)) | The outdoor fan motor’s position or speed signal is faulty. | Fault – service needed |
| H8 (Split, ducted, multi head and cassette systems (varies by series)) | The sensor that measures the current going into the compressor is faulty. | Minor fault |
| H9 (Split, ducted, multi head and cassette systems (varies by series)) | The sensor that reads the outdoor air temperature is faulty. | Minor fault |
| J1 (Split, ducted, multi head and cassette systems (varies by series)) | A refrigerant pressure sensor on the outdoor unit is faulty. | Minor fault |
| J2 (Split, ducted, multi head and cassette systems (varies by series)) | The compressor current sensor is faulty. | Minor fault |
| J3 (Split, ducted, multi head and cassette systems (varies by series)) | The temperature sensor on the pipe leaving the compressor is faulty. | Minor fault |
| J4 (Split, ducted, multi head and cassette systems (varies by series)) | The sensor that reads the low pressure side temperature is faulty. | Minor fault |
| J5 (Split, ducted, multi head and cassette systems (varies by series)) | The temperature sensor on the suction pipe into the compressor is faulty. | Minor fault |
| J6 (Split, ducted, multi head and cassette systems (varies by series)) | The temperature sensor on the outdoor coil is faulty. | Minor fault |
| J7 (Split, ducted, multi head and cassette systems (varies by series)) | The temperature sensor on the liquid refrigerant pipe is faulty. | Minor fault |
| J8 (Split, ducted, multi head and cassette systems (varies by series)) | A temperature sensor on the refrigerant piping, the liquid or oil pipe, is faulty. | Minor fault |
| J9 (Split, ducted, multi head and cassette systems (varies by series)) | The temperature sensor on the gas refrigerant pipe is faulty. | Minor fault |
| JA (Split, ducted, multi head and cassette systems (varies by series)) | The sensor that measures the high side, discharge, refrigerant pressure is faulty. | Minor fault |
| JC (Split, ducted, multi head and cassette systems (varies by series)) | The sensor that measures the low side, suction, refrigerant pressure is faulty. | Minor fault |
| L0 (Split, ducted, multi head and cassette systems (varies by series)) | The inverter system that drives the compressor has a fault. | Fault – service needed |
| L1 (Split, ducted, multi head and cassette systems (varies by series)) | The inverter circuit board in the outdoor unit has failed. | Fault – service needed |
| L3 (Split, ducted, multi head and cassette systems (varies by series)) | The electrical component box in the outdoor unit is running too hot. | Fault – service needed |
| L4 (Split, ducted, multi head and cassette systems (varies by series)) | The heatsink that cools the inverter electronics is running too hot. | Fault – service needed |
| L5 (Split, ducted, multi head and cassette systems (varies by series)) | The inverter detected a sudden current spike, often pointing to a compressor or wiring problem. | Fault – service needed |
| L6 (Split, ducted, multi head and cassette systems (varies by series)) | The inverter detected a current spike on the AC side. | Fault – service needed |
| L8 (Split, ducted, multi head and cassette systems (varies by series)) | The inverter compressor is drawing too much current. | Fault – service needed |
| L9 (Split, ducted, multi head and cassette systems (varies by series)) | The compressor failed to start, it may be locked or seized. | Fault – service needed |
| LA (Split, ducted, multi head and cassette systems (varies by series)) | The power transistor in the inverter has failed. | Fault – service needed |
| LC (Split, ducted, multi head and cassette systems (varies by series)) | Communication between the inverter and the outdoor unit’s control board has failed. | Fault – service needed |
| P1 (Larger ducted systems on three phase power) | The three phase power supply is unbalanced or missing a phase. | Fault – service needed |
| P3 (Split, ducted, multi head and cassette systems (varies by series)) | The temperature sensor inside the outdoor electrical box is faulty. | Minor fault |
| P4 (Split, ducted, multi head and cassette systems (varies by series)) | The temperature sensor on the inverter heatsink is faulty. | Minor fault |
| P9 (Splits with a built in humidifier such as the Ururu Sarara (US7)) | The fan motor in the humidifier unit has a fault. During installer commissioning P9 can also simply signal that the automatic refrigerant charge has finished. | Minor fault |
| PA (Splits with a built in humidifier such as the Ururu Sarara (US7)) | The heater wire in the humidifier unit is broken. During installer commissioning PA can instead mean the refrigerant cylinder ran empty during automatic charging. | Minor fault |
| PJ (Split, ducted, multi head and cassette systems (varies by series)) | The outdoor unit’s capacity setting is wrong or missing, usually after a circuit board has been replaced. | Fault – service needed |
| U0 (Split, ducted, multi head and cassette systems (varies by series)) | The system has detected a refrigerant shortage, usually from a slow gas leak. | Fault – service needed |
| U1 (Larger ducted systems on three phase power) | The three phase power supply has a phase reversed or missing, so the unit will not run. | Fault – service needed |
| U2 (Split, ducted, multi head and cassette systems (varies by series)) | The unit has detected a power supply problem such as a voltage drop or overvoltage. | Fault – service needed |
| U3 (Ducted and multi head systems) | The commissioning check run was never completed, or its transmission failed, so the system will not operate normally. | Fault – service needed |
| U4 (Split, ducted, multi head and cassette systems (varies by series)) | The indoor and outdoor units have lost communication with each other. | Fault – service needed |
| U5 (Systems with a wired controller, mainly ducted and cassette) | The indoor unit and the wall controller have lost communication. | Fault – service needed |
| U6 (Multi head and multi split systems) | Communication between the indoor units has failed. | Fault – service needed |
| U7 (Multi head and multi split systems) | Communication between outdoor units, or within the outdoor unit’s own control system, has failed. | Fault – service needed |
| U8 (Systems with a wired controller, mainly ducted and cassette) | The main and secondary wall controllers cannot talk to each other. | Fault – service needed |
| U9 (Multi head and multi split systems) | Another indoor or outdoor unit on the same system has a fault that is stopping this unit. | Fault – service needed |
| UA (Split, ducted, multi head and cassette systems (varies by series)) | The indoor and outdoor units are not a valid combination, the system settings do not match the connected units, or the unit has detected a power supply or sensor wiring problem between the units. | Fault – service needed |
| UC (Systems with a centralised controller, mainly ducted) | Two units or controllers have been given the same centralised control address. | Fault – service needed |
| UE (Systems with a centralised controller, mainly ducted) | The indoor unit has lost communication with the centralised controller. | Fault – service needed |
| UF (Multi head and multi split systems) | The refrigerant piping and the control wiring do not match up between units, so the system is not set up correctly. | Fault – service needed |
| UH (Split, ducted, multi head and cassette systems (varies by series)) | A system level fault, usually in the transmission wiring between units. | Fault – service needed |
| UJ (Split, ducted, multi head and cassette systems (varies by series)) | An accessory device connected to the system has a transmission fault. | Fault – service needed |
The most serious Daikin fault codes explained
What does Daikin fault code U0 mean? (Split, ducted, multi head and cassette systems (varies by series))
The system has detected a refrigerant shortage, usually from a slow gas leak.
Likely causes:
- Refrigerant leak in the pipework, flare joints or coils
- Service valves not fully opened after installation
- Very dirty filters or coils mimicking low gas flow
Safe checks before you call:
- Clean the return air filters and make sure nothing is blocking the indoor unit airflow
- Turn the system off at the isolator or breaker, wait 5 minutes, then restart it
What does Daikin fault code U1 mean? (Larger ducted systems on three phase power)
The three phase power supply has a phase reversed or missing, so the unit will not run.
Likely causes:
- A phase has dropped out at the switchboard or in the street supply
- Blown fuse on one phase
- Wiring changed during recent electrical work
Safe checks before you call:
- Turn the system off at the isolator or breaker, wait 5 minutes, then restart it
- Check the outdoor unit isolator switch next to the unit is switched on
What does Daikin fault code U2 mean? (Split, ducted, multi head and cassette systems (varies by series))
The unit has detected a power supply problem such as a voltage drop or overvoltage.
Likely causes:
- Brief brownout or blackout in the street supply
- Voltage dips when other heavy appliances start
- Loose power connection or a failing outdoor circuit board
Safe checks before you call:
- Turn the system off at the isolator or breaker, wait 5 minutes, then restart it
- Check the outdoor unit isolator switch next to the unit is switched on
What does Daikin fault code U3 mean? (Ducted and multi head systems)
The commissioning check run was never completed, or its transmission failed, so the system will not operate normally.
Likely causes:
- Installer check operation not run after installation or board replacement
- Control wiring fault between units
Safe checks before you call:
- Turn the system off at the isolator or breaker, wait 5 minutes, then restart it
What does Daikin fault code U4 mean? (Split, ducted, multi head and cassette systems (varies by series))
The indoor and outdoor units have lost communication with each other.
Likely causes:
- Interconnecting cable damage or a loose terminal
- Power lost to the outdoor unit
- Indoor or outdoor circuit board failure
Safe checks before you call:
- Check the outdoor unit isolator switch next to the unit is switched on
- Turn the system off at the isolator or breaker, wait 5 minutes, then restart it
What does Daikin fault code U5 mean? (Systems with a wired controller, mainly ducted and cassette)
The indoor unit and the wall controller have lost communication.
Likely causes:
- Controller cable damage or a loose connection
- Faulty wall controller
- Electrical noise interfering with the controller wiring
Safe checks before you call:
- Turn the system off at the isolator or breaker, wait 5 minutes, then restart it
What does Daikin fault code U6 mean? (Multi head and multi split systems)
Communication between the indoor units has failed.
Likely causes:
- Control wiring fault between indoor units
- One indoor unit has lost power
- Circuit board fault in one indoor unit
Safe checks before you call:
- Turn the system off at the isolator or breaker, wait 5 minutes, then restart it
What does Daikin fault code U7 mean? (Multi head and multi split systems)
Communication between outdoor units, or within the outdoor unit’s own control system, has failed.
Likely causes:
- Control wiring fault between outdoor units
- Outdoor circuit board fault
Safe checks before you call:
- Turn the system off at the isolator or breaker, wait 5 minutes, then restart it
- Check the outdoor unit isolator switch next to the unit is switched on
What does Daikin fault code U8 mean? (Systems with a wired controller, mainly ducted and cassette)
The main and secondary wall controllers cannot talk to each other.
Likely causes:
- Controller wiring fault
- Both controllers set as main, or both set as sub
- Faulty controller
Safe checks before you call:
- Turn the system off at the isolator or breaker, wait 5 minutes, then restart it
What does Daikin fault code U9 mean? (Multi head and multi split systems)
Another indoor or outdoor unit on the same system has a fault that is stopping this unit.
Likely causes:
- A fault on a different head unit in a multi system
- Wiring or piping fault on another part of the system
Safe checks before you call:
- Turn the system off at the isolator or breaker, wait 5 minutes, then restart it
What does Daikin fault code UA mean? (Split, ducted, multi head and cassette systems (varies by series))
The indoor and outdoor units are not a valid combination, the system settings do not match the connected units, or the unit has detected a power supply or sensor wiring problem between the units.
Likely causes:
- Mismatched indoor and outdoor models after a part replacement
- Wrong field settings after service work
- Too many or incompatible heads on a multi system
- Power supply problem on the indoor or outdoor unit circuit
- Remote temperature sensor wire loose or disconnected (wired sensor installs)
Safe checks before you call:
- Turn the system off at the isolator or breaker, wait 5 minutes, then restart it
What does Daikin fault code UC mean? (Systems with a centralised controller, mainly ducted)
Two units or controllers have been given the same centralised control address.
Likely causes:
- Address setting duplicated during installation or board replacement
- Centralised controller configuration error
Safe checks before you call:
- Turn the system off at the isolator or breaker, wait 5 minutes, then restart it
Fault confirmed? Here is what to do next
A fault code is the starting point, not the fix. Start here:
- Air conditioner repairs – how we diagnose and fix Daikin faults across Adelaide. Our fault find covers the full diagnosis, and it is on us if you go ahead with the repair.
- Repair or replace calculator – whether fixing your current system is the smarter money.
- Service and maintenance – regular servicing prevents most of the faults on this page.
- Air conditioner fault code lookup – all 15 brands in one place.
- All calculators and tools
Call us on 08 8296 7888 or book online and we will call or text you back ASAP.
Sources for this page
Every Daikin code above is checked against these Australian documents. Open them yourself to verify anything on this page:
- b0568f 4ca841c28e684a7da083c6b67322f8e0 (PDF) (daikin.com.au)
- b0568f faf1a8e64a124b4697e1d153f7b504a3 (PDF) (daikin.com.au)
- daikin error codes (skyconair.com.au)
- daikin air conditioner error codes (valleyairconditioning.com.au)
- daikin fault codes (controlsdirect.com.au)
- daikin error codes system (glowhce.com.au)
- daikin error codes (aircaresolutionsnsw.com.au)
- daikin error codes indoor unit (glowhce.com.au)
- daikin error codes outdoor unit (glowhce.com.au)
Daikin fault code FAQs
Where do I find the fault code on a Daikin air conditioner?
Check the remote or wall controller display first. Some models flash the indoor unit’s lamps in a pattern instead; the table above lists documented lamp patterns alongside their codes. If nothing is showing, the code may only appear while the fault is active.
Can I clear a Daikin fault code myself?
You can reset the system by turning it off at the isolator or breaker for five minutes. If the code stays gone, it was a one-off. If it returns, the fault is real and needs a licensed technician, and repeated resets can cause further damage on compressor or refrigerant faults.
Does a Daikin fault code mean I need a new air conditioner?
Usually not. Most codes point to repairable faults like sensors, fan motors or drainage. Our fault find gives you an honest verdict either way, and the fee is credited if you repair with us.
Are these Daikin fault codes correct for Australian models?
Yes. Every code on this page was checked against Australian documentation (daikin.com.au, skyconair.com.au, valleyairconditioning.com.au), not overseas lists, because the same code can mean different things in different markets. Meanings still vary between model series, so treat this page as reference and cross-check your unit’s manual.
Written by Oliver Hastings, T&K Airpower. Last updated 01/08/2026. Compiled from Australian sources including daikin.com.au, skyconair.com.au, valleyairconditioning.com.au, controlsdirect.com.au, so you can check every code against the official documentation. Fault code meanings vary between model series and controllers, so treat this page as reference only and never remove panels or work on the refrigeration or electrical parts of the system yourself.
