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We get the story
What it's doing, when it started, how old the unit is. Half the diagnosis is knowing what changed.
What every common Daikin fault code means, what you can safely check yourself, and when to call a tech. From the crew that repairs them, since 1991.
Daikin Error Codes Explained: A Sydney Technician's Guide
Daikin Fault Codes
Reading a Daikin Error Code
Daikin shows a two-character code on the remote or indoor unit. Note it down before you do anything - it tells the tech half the story before we arrive.
Got a Daikin flashing a fault code? Here is how to pull it off the unit. Grab the wireless remote and point it at the indoor unit. Press and hold the CANCEL button. After about 5 seconds the temperature display shows "00" and starts flashing. Keep tapping CANCEL to step through the codes. The unit gives a short beep at each step and a long beep when it lands on the code that is actually stored. That long beep is your fault code. Write the two characters down before you do anything else. On a wired wall controller (the BRC type) press the Cancel or Inspection button and the code shows straight on the screen.
Here is me pulling a fault code off a Daikin split:
The code is two characters. The first letter tells you the area. U is communication and power, E is the outdoor unit, A and C are the indoor unit and its sensors, F and H are pressure and the compressor, J is a sensor, L and P are the inverter. The number narrows it down. Some you can clear yourself with a restart or a filter clean. Others mean a real fault that needs a licensed tech with gauges. The full list below tells you which is which.
We have repaired Daikin since 1991. If your code is not here, read it to us on (02) 9820 4500 and we will tell you what it likely means.
One thing first: a single flash of a code after a power flicker or a storm is often nothing - restart the unit at the isolator and see if it returns. A code that comes straight back is a real fault. Repeatedly resetting a unit that keeps throwing the same code can turn a small problem into a dead compressor, so do not nurse it.
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Most Common Codes
The Daikin Codes We See Most
Top four. The full list is below.
U4 or UF - communication error
The indoor and outdoor units have stopped talking. Often a wiring fault rather than a dead board. Safe check: restart at the isolator for 5 minutes. If it returns, it needs a tech to test the interconnect wiring.
U0 - refrigerant shortage
The system is low on gas, which means a leak. Cooling fades and the unit may ice up. Not a DIY fix - it needs a licensed tech to find the leak, repair it and regas. Do not keep running it low.
E3 - high pressure fault
The outdoor unit has tripped on high pressure, often from a blocked or dirty condenser. Safe check: clear leaves and debris off the outdoor unit and make sure it can breathe. If it returns after that, call a tech.
A6 - indoor fan motor fault
The indoor fan is not running properly or is blocked. Safe check: make sure nothing is jamming the fan and the filters are clean. If clear and it persists, the motor likely needs replacing - around $300 to $500 fitted.
The Full Daikin Error Code List
U codes - communication and power
U0 - low refrigerant. The system is short on gas, usually a leak. Needs a leak find and regas, $200 to $350 for a top-up once the leak is sorted.
U1 - reverse or open phase. A power wiring phase problem, mostly on three-phase ducted. An electrician or tech checks the supply.
U2 - voltage fault. Supply voltage too low or too high to the outdoor unit. Have the supply and connections checked.
U3 - test run not done. The commissioning step was skipped after an install or a board swap. A tech runs the check operation.
U4 / UF - communication error. Indoor and outdoor not talking, usually the interconnect wiring. Restart first; if it comes back, the wiring needs testing, $180 to $400.
U5 - indoor to remote. The wall controller and indoor unit have lost contact. Often the controller cable.
U7 - outdoor to outdoor. Multi or VRV wiring between outdoor units. A tech job.
UA - unit mismatch. Wrong indoor and outdoor pairing, or too many heads on a multi. The combination needs checking.
UH - address fault. System addressing not set, usually after a board change. Re-commissioned by a tech.
A and C codes - indoor unit and sensors
A0 - external protection. A safety device wired to the indoor unit has tripped. Needs investigating.
A1 - indoor PCB fault. The indoor control board. Confirmed by testing before replacing, $400 to $700.
A3 - drain system. The condensate drain or pump. Often a blocked drain, $120 to $150 to clear.
A5 - high pressure or freeze protection. An indoor protection trip. Check airflow and filters first.
A6 - indoor fan motor. Fan motor jammed or overloaded, $300 to $500 fitted.
A7 - swing flap motor. The louvre motor. A minor part, quoted after testing.
A9 - expansion valve (indoor). The electronic expansion valve. Tested before replacing.
AF - drain level high. Water sitting in the tray, drain or pump blocked. Clear and test.
AH - filter sign (not a fault). Just a reminder to clean your filter. Wash it and reset.
AJ - capacity setting. Wrong capacity setting after a board swap. A tech resets it.
C4 / C5 / C9 - sensor faults. Heat exchanger, gas pipe or suction thermistors giving bad readings, $250 to $300 fitted.
CJ - remote sensor. The thermistor inside the wall controller. Often the controller itself.
E codes - outdoor unit
E1 - outdoor PCB fault. The outdoor control board, confirmed by testing before replacing, $400 to $700.
E3 - high pressure. Dirty condenser or restricted airflow. Clean the outdoor unit first.
E4 - low pressure. Often low gas or a restriction. Needs gauges.
E5 - compressor overload. The compressor is straining, often from heat or low gas. Needs diagnosis - do not keep running it.
E6 - compressor start fault. Frequently a capacitor or the compressor itself. We test the capacitor first, $150 to $180 if that is it.
E7 - outdoor fan motor. The outdoor fan not spinning, $300 to $500 fitted.
E9 - expansion valve (outdoor). The outdoor electronic expansion valve. Tested before replacing.
EA - 4-way valve. The reversing valve. Cools but will not heat, or the other way round. Quoted after testing.
F, H and J codes - pressure, compressor and sensors
F3 - discharge pipe too hot. The compressor running hot, often low gas. Needs gauges.
F6 - high pressure in cooling. Dirty condenser or an overcharge. Clean the outdoor unit first.
H0 / H6 - compressor sensor or position. The compressor control sensors. Diagnosed before any part goes in.
H8 - current sensor. A current reading fault on the outdoor board. Tested first.
H9 - outdoor air sensor. The outdoor thermistor, $250 to $300 fitted.
J3 / J5 / J6 - outdoor sensors. Discharge, suction or coil thermistors, $250 to $300 fitted.
L and P codes - inverter
L1 / L5 - inverter fault. The inverter or compressor drive circuit. Needs proper diagnosis.
L3 / L4 - inverter overheating. The electrical box or heatsink getting too hot, often airflow or a dirty unit. Cleaned and tested.
L8 - compressor overcurrent. The compressor drawing too much. Diagnosed before running again.
P1 - voltage imbalance. A power supply imbalance to the inverter. Supply checked.
P4 - heatsink sensor. The inverter heatsink thermistor, tested before replacing.
Common Factors
What's Actually Gone Wrong
Here's what we find when a unit's not cooling, roughly most common first, and what each one costs to sort. If the unit's frozen over or leaking water, that ties in with cooling too. We've got separate pages on ice on the unit and water leaks if that's what you're seeing.
Restart at the isolator
Turn the system off at the isolator switch by the outdoor unit, wait five minutes, switch it back on. This clears one-off codes from power flickers and storms safely. If the code returns, it is a real fault.
Wash the filters
Pop the front off the indoor unit, pull the filters, rinse under the tap and let them dry. Choked filters trigger airflow and fan-related codes and reduce cooling. Safe to do yourself anytime.
Clear the outdoor unit
Make sure the outdoor unit can breathe – no leaves, garden growth or junk piled against it. A choked condenser causes high-pressure codes like E3. Clearing it is safe and free.
What you should NOT do yourself
Do not open the refrigerant circuit, add gas, or pull apart the electricals – all of that legally needs a licensed and ARCtick-certified tech. And do not keep resetting a unit that throws the same code repeatedly; you can cook the compressor.
When to Call a Technician
Call a tech when a code comes straight back after a restart and a filter and outdoor-unit clean, when the code points to gas (U0, E4, F3), the compressor (E5, E6, H6, L5) or a sensor or board, or any time the unit is icing up, dripping water or tripping the breaker. Those are not DIY territory. A standard diagnostic call is $250 plus GST and we quote the fix before we touch anything. We carry common Daikin parts on the van, so a lot of these get sorted same visit.
Diagnosis Process
Daikin Repairs, Done Properly
We do not throw parts at a code and hope. We read the fault, put gauges on if it is gas-related, test the electricals and sensors, then quote the fix before starting. Daikin is one of our main install brands so we know the gear inside out. Since 1991, 4.8 stars from 280+ reviews. See our full Daikin repairs page or call (02) 9820 4500.
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Gauges on, pressures read
Refrigerant pressures tell us straight away if it's a gas problem or something else.
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Electricals and capacitor tested
We check the capacitor, test the fan motors and go over the electricals for anything on the way out.
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Coils and filters checked
Covers come off so we can see the state of the coils and filters, not guess at them.
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Fixed quote before we fix
Once we know the fault, we quote the repair before we start. You decide. Most jobs get done same visit.
Real Jobs
Code Not Listed?
Daikin uses different code sets across its ranges and some models flash the code via LED patterns rather than a display. Read us the exact characters or count the flashes on (02) 9820 4500 and we will tell you what it likely means and roughly what it costs before we come out.
Licensed and Local
NSW licence 273312C, ARCtick AU13058, $20M public liability, our own techs not subbies. We repair every brand and install Daikin, Panasonic and Actron. Family run since 1991.
FAQ's
Daikin Error Codes - Common Questions
Point the remote at the unit and press the cancel or check button until a code appears, or read it off the indoor unit display. It will be two characters like U4 or E3. Write it down before restarting.
U4 is a communication error between the indoor and outdoor units. It is often a wiring fault rather than a failed board. Restart at the isolator for five minutes; if it returns, a tech needs to test the interconnect wiring.
U0 means the system is low on refrigerant, which means there is a leak. Cooling fades and the coil can ice up. It needs a licensed tech to find and fix the leak then regas – do not keep running it low or you risk the compressor.
You can clear one-off codes with a restart at the isolator, and fix airflow-related codes by washing filters and clearing the outdoor unit. A code that keeps returning is a real fault for a tech. Never reset repeatedly – it can damage the compressor.
A diagnostic call is $250 plus GST. Common fixes: capacitor $150 to $180, sensor $250 to $300, fan motor $300 to $500, gas top-up $200 to $350 once the leak is repaired, board $400 to $700. We quote before any work.
Jay’s Air – Daikin is one of our main install and repair brands. Licence 273312C, ARCtick AU13058, lifetime workmanship warranty on installs, 4.8 stars from 280+ reviews, since 1991. (02) 9820 4500.
If the unit’s under about 10 years and it’s a capacitor, a fan motor or gas, repair it every time. If it’s 12 years plus, running old R22 gas, and the compressor or board’s gone, a new system’s usually the smarter spend. We’ll give you the honest call, not the dearest one. If you’re weighing up a new system, our sizing guide tells you what you actually need.
Yeah, the lot. Daikin, Mitsubishi, Panasonic, Fujitsu, Actron, LG and the rest. Ducted and split, homes and businesses. We do split system repairs and ducted repairs right across Sydney.
Jay’s Air. Family run since 1991, our own blokes not subbies, fixed pricing and no surprises. Licensed (NSW 273312C), ARCtick certified (AU13058), 4.8 stars from 280+ reviews. Give us a bell on (02) 9820 4500 and we’ll get it sorted.