Daikin error codes: what they mean and what to do
If the light on your Daikin indoor unit is flashing and the unit has stopped, it has stored a fault code. Here is how to read the code with your remote, what the common codes mean according to Daikin's own service manual, what you can safely check yourself, and when you need an engineer.
- hold Cancel to start the check
- 5 seconds
- code length on the remote, e.g. U4
- 2 characters
- diagnostic visit, deducted
- £125
- we repair Daikin whoever fitted it
- Any fitter
How a Daikin tells you something is wrong
When a Daikin home unit finds a fault, the operation lamp on the indoor unit blinks. On newer models with the Daikin eye, the eye flashes instead. Many faults stop the unit, but some protection codes clear by themselves once conditions return to normal.
The lamp doesn't tell you which fault it is. For that, you ask the indoor unit for its code with the remote. Daikin codes are two characters, such as U4 or UA.
How to show the error code on your Daikin remote
Hold Cancel
Point the remote at the indoor unit and hold the timer Cancel button for about 5 seconds. 00 flashes in the temperature part of the display.
Step through the codes
Press Cancel again, one press at a time. Each press shows the next code and sends it to the indoor unit.
Listen for the long beep
One or two short beeps mean that code isn't the fault. A long continuous beep means the code on screen is the one stored. Write it down.
Go back to normal
Hold Cancel for 5 seconds to leave. If you leave the remote alone for a minute, it goes back to normal by itself.
Common Daikin error codes
The codes Daikin's service manual lists for its home wall units, in plain English. Most need an engineer, but a few have a simple cause you can check first.
| Code | What Daikin says it means | What you can do |
|---|---|---|
| A1 | Indoor unit circuit board (PCB) fault | Book an engineer. |
| A5 | Indoor coil too cold in cooling (freeze protection) or too hot in heating | Clean the filters and clear the airflow. It clears when the coil recovers. Book us if it returns. |
| A6 | Indoor fan motor fault: the fan isn't turning as it should | Book an engineer. Don't try to turn the fan yourself. |
| C4 | Indoor coil temperature sensor open or short circuit | Book an engineer. |
| C9 | Room temperature sensor fault | Book an engineer. |
| E1 | Outdoor unit circuit board fault | Book an engineer. |
| E5 | Compressor overload (overheating) | Book an engineer. |
| E6 | The compressor failed to start | Book an engineer. |
| E7 | Outdoor fan motor fault: the fan didn't start when it should | Look from a distance for leaves or a cover stopping the fan. If clear, book an engineer. |
| F3 | Discharge pipe temperature too high | Book an engineer. Causes range from the refrigerant charge to a valve or sensor. |
| F6 | High pressure while cooling | Clear space around the outdoor unit and check its fins aren't clogged. Book us if it returns. |
| L5 | Inverter overcurrent | Book an engineer. |
| U0 | Shortage of refrigerant | Book an F-Gas certified engineer. A split system is sealed, so low gas usually means a leak. |
| U2 | Power supply voltage problem or a brief power cut | Do a power reset. If it keeps happening, have the supply checked. |
| U4 | Indoor and outdoor units can't communicate | Do a power reset. If it returns, the wiring or a circuit board needs checking. |
| UA | Indoor and outdoor units don't match, or the signal between them is faulty | Book an engineer. Most often seen after an install or a part change. |
| UH | Multi-split only: another indoor unit has a U0, UA or A5 fault | Check the code on each of the other indoor units. |
Source: Daikin service manual ESIE20-11A (Split New Perfera R32) and Daikin's How to Check Error Codes guide, checked October 2026.
Safe checks before you book
Safe for anyone to do. If the same code comes back, stop resetting and book a visit.
- Write down the code and the model number from the label on the side of the indoor unit
- Check the remote's batteries, and that it's set to the mode you want
- Switch off, then clean the air filters behind the front panel
- Clear leaves, bins or covers from around the outdoor unit, keeping hands away from the fan
- Do a power reset: switch off at the isolator or breaker, wait a few minutes, switch back on
What a Daikin repair visit costs
The diagnostic visit covers the first hour on site and comes off the bill if you go ahead. Send us the code and model number when you book. We repair Daikin systems whoever installed them.
- from£125inc. VAT
Repair diagnostic visit
First hour on site, deducted if you go ahead
Daikin error code questions
How do I clear an error code on my Daikin?
Daikin's service manual says that once the cause is fixed, pressing ON/OFF on the remote resets the code. Some codes need a power reset, and some protection codes clear by themselves. If the cause is still there, the code comes back and needs an engineer.
What does U4 mean on a Daikin air conditioner?
U4 means the indoor and outdoor units have stopped communicating. Daikin's checks include the power supply, the wiring between the units and the circuit boards. Try one power reset at the isolator. If U4 comes back, book an engineer.
What does U0 mean on a Daikin?
U0 means the system has detected a shortage of refrigerant. Daikin's manual also lists a faulty sensor or a closed valve as possible causes, so it needs testing before anyone adds gas. Refrigerant work must be done by an F-Gas certified engineer, and ours are F-Gas and REFCOM certified.
Why does my Daikin show A5 in winter?
In heating, A5 means the indoor coil has gone above 65°C, so the unit stops to protect itself. Daikin's first checks are blocked airflow and dirty filters. Clean the filters and clear the space around the indoor unit. If it keeps happening, book an engineer.
My Daikin remote has no Cancel button. How do I see the code?
Daikin's guide gives a second method for some remotes: press TEMP up, TEMP down and MODE together, then change each digit with the TEMP buttons until you hear a long beep. Newer remotes can differ, so check your model's user reference guide on daikin.eu, or send us the model number.