This site is not affiliated with Daikin; this is an independent explanation.
This Daikin error code list explains the codes that show on the indoor display or blink on the lamp of a Daikin split, inverter or cassette AC. Each code is a letter plus a digit, such as L5, U0, E9 or C4. The letter points to an area of the AC and the digit points to the exact fault that the control board found.
Meanings can change between models and years, so treat this page as the common meaning on most models. Your remote, the sticker inside the front panel or the user manual has the final table. Anything that touches wiring, the circuit board, the outdoor unit or the gas is work for a trained Daikin technician, so the steps below only cover what is safe for you to do at home.
Common causes
1Power supply problem or voltage swings
How to tellCode appears after a power cut, a storm or when other heavy loads start
What fixes itSwitch the AC off at its MCB for 5 minutes, then restart; fit a proper stabiliser if voltage is poor
2Dirty filter or blocked indoor coil
How to tellWeak cooling, ice on the pipe, or a code linked to airflow or freezing
What fixes itClean the filters and let any ice melt fully before restarting
3Sensor (thermistor) reading out of range
How to tellCodes like C4, C9 or H9 with strange cooling or early cut off
What fixes itNeeds a technician to test or replace the sensor
4Indoor to outdoor communication fault
How to tellU4 or UA, indoor lamp blinks, outdoor unit does not start
What fixes itCheck the AC has power at both ends, then call service for the cable and boards
5Blocked drain or float switch trip
How to tellA3 with water dripping, a full drain pan or a cassette that stops
What fixes itStop the AC, clear visible drain blockage; a technician checks the pump
6Compressor or inverter protection
How to tellL5, E5, E6 or E9 style codes after repeated start attempts
What fixes itDo not keep restarting; book authorised service
7Low refrigerant or a leak
How to tellU0 with poor cooling, frost on the thin pipe or an oily joint
What fixes itRefrigerant work is for a trained technician only
How to fix it, step by step
Note the code and when it appears
Write down the exact code and what the AC was doing: just switched on, running for an hour, or after rain. Check whether it is a lamp blinking or a code on a display. A clear note saves the technician time and helps you match the code below.
Switch off at the MCB for five minutes
Turn the AC off with the remote, then switch off its own breaker at the board. Wait five minutes so the control board resets, switch back on and start the AC again. Many one time codes after a power dip disappear with this alone.
Clean the washable air filters
Open the front panel, slide out the mesh filters and rinse them under a tap with plain water. Let them air dry out of the sun and refit. A choked filter leads to coil icing and several protection codes.
Check the room, the remote and the mode
Keep doors closed and make sure nothing blocks the air flow of the indoor unit. Replace the remote batteries and select Cool at a normal set temperature. A wrong mode can look like a fault.
Look for water or ice, never open the casing
If you see ice on the indoor unit or water at the outlet, turn the AC off and run only the fan mode for an hour to melt it. Do not remove the panels beyond the filter door and never open the outdoor unit.
Restart once, then stop if the code returns
Should it flash again soon after starting, leave the AC off. Repeated starts can stress the compressor and turn a small fault into a costly one.
Book authorised Daikin service with your notes
Share the model name from the indoor label, the code and the steps you tried. Ask the technician to confirm the code on your model and to explain the repair before work starts. See also our AC not working checklist.
Daikin error code list for split and inverter ACs
| Code | Usual meaning on most models | Who fixes it |
|---|---|---|
| 00 | Normal, no fault stored | Nothing to fix |
| A1 | Indoor control board problem | Technician |
| A3 | Drain water level problem | You (clear drain), then technician |
| A5 | Freeze up or high pressure protection | You (filters), then technician |
| A6 | Indoor fan motor stuck or overloaded | Technician |
| C4 | Indoor coil temperature sensor fault | Technician |
| C9 | Room temperature sensor fault | Technician |
| E1 | Outdoor board fault | Technician |
| E5 | Compressor motor locked or overloaded | Technician |
| E7 | Outdoor fan motor fault | Technician |
| E9 | Expansion valve fault | Technician |
| L5 | Inverter or compressor overcurrent | Technician |
| U0 | Refrigerant shortage | Technician |
| U2 | Supply voltage out of range | You (check power), then technician |
| U4 or UA | Indoor and outdoor not communicating | Technician |
Some older or simpler models use fewer codes, and a few use the same code for two causes. That is why the label inside your unit matters more than any list on the web.
Reading L5, U0, U2 and E9 in plain words
L5 means the inverter board saw too much current when the compressor tried to run. It can follow a voltage dip, but it also points to a weak compressor or board, so a technician must test it.
U0 is the code people fear most because it points to low refrigerant. The gas does not get used up, so low gas means a leak, and finding it needs proper tools.
U9 is seen on multi room systems when another indoor unit has a fault, so look at the other rooms too. U2 says the supply voltage is too low, too high or unsteady. See whether fans and lights also sag or trip when the AC starts.
E9 is about the electronic expansion valve, the part that meters refrigerant. It is outdoor side work.
Your living room AC cools for ten minutes and then the lamp blinks twice with U4 on the remote screen. The indoor unit has power but cannot talk to the outdoor unit, so the compressor never starts. Check that the outdoor isolator is on, then call service.
Cassette, ceiling and inverter models behave a little differently
Cassette and ducted Daikin units (the daikin cassette ac a3 error code is a common search) often show A3 because they use a drain pump with a float switch. If the pump fails or the drain line slopes wrongly, water rises and the AC stops to protect the ceiling. Inverter splits add inverter board codes such as L5, while basic non inverter models may show only a few sensor and fan codes.
Do not assume a code from a friend's AC applies to yours. Compare the model number on the indoor label and ask the service centre to confirm.
What makes a Daikin repair cost more
Sensors and filters are the cheap end. Costs rise when the repair needs an outdoor board, a fan motor, a compressor, a leak search or refilling, or when the unit is high on a wall or on an upper floor and needs extra equipment to reach. Before you say yes, get the faulty part named and the price put on paper.
Opening the unit yourself or using an unqualified person can void the warranty and is unsafe. Gas and electrical work must be done by a trained technician.
How to avoid repeat codes
Clean the filters every two to four weeks in the cooling season, keep the outdoor unit clear of dust, cloth and water, and book a yearly service before summer. Use a fixed supply with a good breaker and not an extension board. For codes of other brands, the AC error codes overview shows how the families compare, and the single code page for Daikin F3 and Daikin U4 go deeper.
Frequently asked questions
What does the L5 error code mean on a Daikin AC?
On most models L5 means the inverter saw an overcurrent when starting the compressor. A voltage dip can trigger it once, but if it repeats the board or compressor needs a technician.
What is the U0 error code in Daikin?
U0 usually means refrigerant shortage. Because gas is sealed in the system, low gas points to a leak. Do not refill it yourself; ask authorised service to find the leak.
Daikin E9 error code: can I fix it myself?
No. E9 normally refers to the expansion valve in the outdoor side, so only a technician should check it. You can only reset power and confirm the AC has steady supply.
What does U2 mean on a Daikin?
U2 means the supply voltage is out of range. Check for power fluctuation, loose supply wiring or a weak stabiliser, and ask an electrician to look if the room lights sag each time the compressor starts.
What does the 00 code mean on Daikin?
On most models 00 means the error history is clear or no fault is stored. If the AC is working badly with 00 shown, the cause is probably airflow, gas or a sensor reading, so check service history.
Where can I get a Daikin error code list pdf?
The user manual or the service page for your exact model has the official table. Find the model name on the indoor label and request the matching code sheet from the authorised centre.