Error Code Library
Daikin Air Conditioner Error Codes
Daikin air conditioner error codes look cryptic at first, yet they follow a tidy system once you know the pattern. This guide explains how the letters and numbers are grouped, how to bring a stored code up on your remote or wall controller, and what each common code points to. You will also find safe checks you can do yourself and clear advice on when a licensed technician is the right call.
The Basics
What Is a Daikin Error Code Telling You?
Every Daikin system has a control board that watches temperatures, currents, pressures and communication signals. When a reading falls outside the safe window, the board stops the system and stores a short code. That code is a starting point for diagnosis rather than a final verdict. In other words, it tells you which part of the system raised the alarm, not always why.
For example, a code about the outdoor fan could come from a jammed blade, a worn motor or a faulty drive circuit. Likewise, a code about indoor coil temperature could come from a dirty filter or a refrigerant leak. Because of this, the same code can have a quick fix in one home and a parts replacement in another.
Most Daikin fault codes are two characters long. The first is a letter that names the area of the system, and the second narrows it down. Knowing the letter alone already tells you a lot, so we start there below. If you want broader help with symptoms rather than codes, our air conditioner troubleshooting guide covers noises, leaks and weak airflow.
How Codes Are Grouped
How Are Daikin Fault Codes Structured?
Daikin uses the same letter groups across most of its residential and light commercial range. As a result, once you learn the groups, you can make sense of codes on a wall split, a ducted system or a multi split. The exact meaning of a few codes still shifts between model series, and we flag those cases on each code page.
A Codes, Indoor Unit
These relate to the indoor unit itself. They cover the indoor control board, drain water level, indoor coil protection and the indoor fan motor.
C Codes, Indoor Sensors
C codes point to the temperature sensors inside the indoor unit, called thermistors. They measure the coil and the room air so the system can control itself.
E Codes, Outdoor Protection
E codes come from the outdoor unit. They include the outdoor board, high and low pressure protection, compressor protection and the outdoor fan.
F and H Codes, Outdoor Sensing
These flag temperature and pressure sensing problems in the outdoor unit, such as the discharge pipe sensor or the compressor sensing circuit.
J and L Codes, Sensors and Inverter
J codes cover outdoor pipe sensors, such as the suction pipe thermistor. L codes relate to the inverter board that drives the compressor, including overcurrent trips.
U Codes, System and Communication
U codes describe whole system issues. Typical examples are lost communication between units, abnormal supply voltage and a suspected refrigerant shortage.
Once you know the group, you can usually tell whether the trouble sits inside or outside. That alone helps when you call for a booking, because the technician can prepare for the right unit.
Reading the Code
How Do You Find the Code on a Daikin System?
How you see the code depends on the type of system and controller you have. Some Daikin units show the code straight away, while others only flash a light until you ask for the details. Here is how it generally works.
Look at the indoor unit lights
Many wall splits have no screen on the indoor unit. Instead, the operation lamp blinks to show a fault is stored. The blink itself does not tell you the code.Use the wireless remote check function
On many Daikin remotes, you hold the Cancel or Timer Cancel button for around five seconds until the display shows 00. Then you press the same button repeatedly while pointing at the indoor unit. When the shown code matches the stored fault, the unit gives a long beep.Check the wired wall controller
Ducted and cassette systems usually have a wired controller. It normally shows the two character code on screen, sometimes with a unit number. An inspection or test button can bring it back if it has cleared.Write it down before resetting
Note the code, the time, the weather and what the system was doing. A reset can clear the display, so having it on paper saves time for the technician.
Button names and steps vary between remote models, so treat this as general guidance. If your remote has a different layout, your owner manual will show the right sequence. Older remotes may also show only a simple fault icon rather than a code.
Code Directory
Which Daikin Codes Do We Explain in Detail?
The codes below are among the ones households report most often. Each link opens a full page with likely causes ranked from simple to serious, safe checks, what a technician tests, and answers to common questions.
A1, Indoor Board Fault
The indoor control board has detected a problem with itself or its supporting circuits.
A3, Drain Water Level
The float switch has sensed water building up in the drain pan, so cooling stops.
A5, Indoor Coil Protection
The indoor coil got too cold in cooling or too hot in heating, often due to airflow.
A6, Indoor Fan Motor
The indoor fan is not turning at the speed the board expects, or has locked.
C4, Indoor Coil Sensor
The thermistor on the indoor heat exchanger is giving an impossible or missing reading.
E1, Outdoor Board Fault
The outdoor control board has found a fault in its own operation.
E3, High Pressure Trip
Refrigerant pressure climbed above the safe limit and the protection switch acted.
E5, Compressor Protection
The compressor was overloaded, overheated or locked, so the system shut it down.
E7, Outdoor Fan Motor
The outdoor fan has stalled, slowed or failed to start.
H0, Compressor Sensing
The outdoor board cannot get a reliable signal from the compressor sensing circuit.
L5, Inverter Overcurrent
Current from the inverter to the compressor spiked above the safe limit.
U4, Communication Loss
The indoor and outdoor units have stopped talking to each other.
Quick Reference
What Do Other Common Daikin Codes Mean?
Beyond the detailed pages, you may see other codes on your controller. The short list below gives the general meaning only. Because some of these vary by model, a technician should confirm them on site.
Indoor and Sensor Codes
- A7, indoor swing flap motor fault on models that report it
- A9, indoor electronic expansion valve fault on models fitted with one
- C5, a second indoor coil thermistor on some models
- C9, indoor suction pipe thermistor
- CJ, the room temperature sensor in the controller or unit
- U5, lost signal between the indoor unit and a wired controller
Outdoor and System Codes
- E4, low pressure protection, often linked to refrigerant loss
- E6, compressor failed to start or locked
- F3, discharge pipe temperature too high
- J5, outdoor suction pipe thermistor
- U0, suspected refrigerant shortage
- U2, supply voltage dropped or fluctuated
You might also see CH on some remotes. In most cases that is a general fault indicator rather than a code in its own right. Therefore, use the remote check function or the wired controller to find the actual code behind it.
Safe First Steps
What Can You Safely Check Before Calling?
Plenty of Daikin faults clear with a few simple checks, especially those linked to airflow or a brief power problem. Even so, there is a clear line between owner checks and technician work. Stay on the safe side of that line and you protect both yourself and the system.
- Note the code and the conditions when it appeared, such as a storm or a very hot afternoon.
- Check the switchboard for a tripped air conditioner breaker, and reset it only once.
- Confirm the outdoor isolator switch is in the on position.
- Remove and wash the indoor filters, then let them dry fully before refitting.
- Clear leaves, bins, plants and stored items away from the outdoor unit.
- Look at the visible end of the drain line outside and clear any mulch or soil from it.
- Replace the remote batteries if the screen is faint or the unit does not respond.
- Do one power reset at the breaker, waiting about five minutes before switching back on.
On the other hand, some actions are never safe for a homeowner. Do not open the indoor or outdoor covers, touch wiring or terminal blocks, or try to free a fan with a tool. Inverter boards can hold a dangerous charge after the power is off. Refrigerant work also requires an ARCtick licensed technician by law in Australia, so leaks, regassing and pressure testing are always professional jobs.
When to Stop
When Should a Daikin Code Mean Calling a Technician?
A single code after a storm that clears with one reset and never returns is often nothing to worry about. However, several patterns point to a real fault that needs testing with proper instruments. If you notice any of the following, switch the system off and book a visit.
The code returns after a reset
If the same code comes straight back, the cause is still present. Repeated restarts can stress the compressor and electronics, so it is better to leave the unit off.
You notice smells, sounds or marks
A burning smell, scorch marks, grinding from a fan or oily stains near pipe joints all call for a technician. Switch off at the breaker and wait for help.
The breaker keeps tripping
A breaker that trips again after reset suggests an electrical fault. Leave it off rather than forcing it back on.
The code involves refrigerant or pressure
Pressure trips and refrigerant shortage codes need gauges and leak testing. Only a licensed technician can handle the gas side of the system.
Getting a Technician Out
Where Can We Send a Technician for a Daikin Fault?
Rapid Air Cooling is a booking and dispatch service. We take your call, record the code and symptoms, and send a licensed technician who works on Daikin systems. We are not a Daikin dealer and we do not claim manufacturer accreditation. Instead, we focus on getting experienced hands to your home with the details already in place.
We book Daikin repairs across five major cities. In Sydney, our Sydney air conditioner repairs page covers the metro area, and the Daikin page for Sydney goes deeper on the range. Melbourne households can start with air conditioner repairs in Melbourne. Further north, see Brisbane air conditioner repairs and Daikin service in Brisbane.
Out west, our Perth repairs page and Perth Daikin page explain local conditions. In South Australia, see Adelaide air conditioner repairs and Daikin in Adelaide. For a broader overview of the brand, visit our national Daikin air conditioning page, or return to our air conditioning service Australia homepage.
Climate and Codes
Why Do Some Codes Show Up More in Certain Seasons?
Australian weather has a strong effect on which codes appear. During long heatwaves in Adelaide and Perth, outdoor units work at their limit, so pressure and compressor protection codes become more common. Meanwhile, humid summers in Brisbane and Sydney push extra water through indoor units, which can bring on drain level codes.
Coastal homes face a slower problem. Salt air gradually corrodes outdoor coils, connectors and terminal blocks, which can lead to communication and sensor faults over time. Summer storms add sudden power interruptions and surges, which often show up as voltage or communication codes the next morning. In Melbourne, cool nights and heating use mean outdoor coils can ice up, so outdoor fan and defrost related trouble rises in winter.
None of this means the weather is to blame for every fault. Still, mentioning recent conditions when you call helps the technician narrow things down faster.
Good to Know
Is There Anything Else Worth Knowing?
A few general points apply to almost every Daikin code. They help you avoid common mistakes and make any repair visit smoother.
Open more detail
First, codes can differ slightly between model series and production years. A code that means one thing on a wall split may mean something narrower on a ducted or multi system. That is why our code pages say so plainly where a meaning varies.
Second, a stored code may stay in memory after the fault clears. The technician can read the history to see how often a fault has happened, which is useful for intermittent problems.
Third, regular servicing reduces many common codes. Clean filters, clear drains and a tidy outdoor coil remove the most frequent causes of airflow, drain and pressure trips. If your system has not been serviced for a while, that alone is worth booking.
Finally, keep your model number handy. It is usually on a label on the side of the indoor unit and on the outdoor unit. Sharing it when you book helps the technician bring likely parts.
Questions
Frequently Asked Questions
Why is my Daikin flashing a light but not showing a code?
Many wall splits have no display on the indoor unit. The flashing lamp shows a fault is stored, and you use the remote check function to find the actual code.
Can I clear a Daikin error code myself?
You can try one power reset at the breaker, waiting about five minutes. If the code returns, the cause is still there and the system needs a technician.
Do Daikin codes mean the same thing on every model?
Most do, but some vary between series. Ducted and multi systems can use a code more narrowly than a wall split. Your model number helps confirm the exact meaning.
Is it safe to keep using my Daikin with a code showing?
Usually the system will not run while the fault is active. If it restarts but the code keeps coming back, switch it off to avoid further damage.
What does CH mean on my Daikin remote?
On many remotes, CH is a general fault indicator rather than a specific code. Use the check function or your wired controller to find the code behind it.
Will a service stop error codes from appearing?
A service cannot prevent every fault, but it removes common causes such as dirty filters, blocked drains and clogged coils. As a result, many airflow and drain codes become less likely.
Do you only handle Daikin systems?
No. We book technicians for most major brands, and our error codes hub covers other manufacturers as well.
Keep Exploring
Where Should You Go Next?
Pick a code below or head to one of our related guides.
Code Lookup
Look Up a Code Across Brands
The same code can mean different things on different brands. These pages compare what each code means on Daikin, Mitsubishi, Panasonic, Samsung, Fujitsu, LG and Actron.
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Reviewed by AC repair and service specialist on 22 October 2026. How we write our articles