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Daikin air conditioner error codes

22 codes that Daikin and Daikin Europe publish for their air conditioners, each with what it means, the likely cause, what you can safely check and when to call an installer. Tap your code:

Air conditioner: do only the checks the maker gives the owner for that code — clean the air filter, clear the air path, switch the power off and on at the plug or circuit breaker. Keep the covers on: refrigerant, wiring and circuit boards are not owner work. Anything else is for the installer or the maker’s service engineer: in the UK and EU only an F-gas certified technician may open the refrigerant circuit. Codes that need one are marked Installer.

Read this first

Daikin wall, ceiling and ducted air conditioners show a fault as a letter and a digit or letter — U4, A5, E7 — on the remote or wired controller, and the Daikin eye or the operation lamp on the indoor unit flashes. The list here is Daikin’s own Error Code Search, the column for Split and Multi Split units: the same code table covers Daikin’s SkyAir and VRV systems, where some codes have extra causes. On a wireless remote the code is hidden until you ask for it: Daikin’s user reference guide for the Perfera (FTXM-A) wall units says to aim the remote at the unit, hold the button its guide shows for about 5 seconds, then press it repeatedly until you hear a long beep; the code is then on the remote’s display. The same guide says the code should be understood and the fault fixed before it is reset, by a licensed installer or your dealer — so the owner checks below are only the ones Daikin gives the owner. Models differ: your model’s manual is the authority.

U4 No communication between indoor and outdoor unit

What it means
The indoor unit and the outdoor unit have stopped talking to each other over the connecting cable, so the system stops.
Likely cause
Daikin lists: the outdoor unit’s power is off; a short circuit or wrong wiring on the indoor–outdoor transmission cable; a system address that does not match; a faulty indoor or outdoor circuit board.
What you can safely check

Air conditioner: do only the checks the maker gives the owner for that code — clean the air filter, clear the air path, switch the power off and on at the plug or circuit breaker. Keep the covers on: refrigerant, wiring and circuit boards are not owner work.

  • Check that the air conditioner’s fuse has not blown and its circuit breaker has not tripped — the first check in Daikin’s guide when the system will not run. Reset the breaker if it has tripped.
When to call an installer
If U4 comes back with the power on, call your installer: the remaining causes are the connecting cable, the address setting and the circuit boards.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

U0 Refrigerant shortage

What it means
The system has detected too little refrigerant, or refrigerant that is not flowing.
Likely cause
Daikin lists: a refrigerant shortage or a blocked refrigerant pipe, a faulty thermistor, a faulty low-pressure sensor, or a faulty outdoor main circuit board.
What you can safely check

Nothing for the owner to check: this one is for an installer.

When to call an installer
Installer Call your installer. A shortage usually means a leak, and only an F-gas certified technician may find and repair it and recharge the system.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

U2 Power supply fault or brief power cut

What it means
The supply voltage was abnormal, or the power dropped out for a moment, and the unit stopped to protect itself.
Likely cause
Daikin lists: an abnormal supply voltage, an instantaneous power failure, or faulty main-circuit wiring.
What you can safely check

Air conditioner: do only the checks the maker gives the owner for that code — clean the air filter, clear the air path, switch the power off and on at the plug or circuit breaker. Keep the covers on: refrigerant, wiring and circuit boards are not owner work.

  • Wait: Daikin’s guide says the unit may stop after a sudden large voltage fluctuation and starts again by itself after about 3 minutes.
When to call an installer
If U2 keeps returning without a power cut, call your installer or an electrician to check the supply and the unit’s wiring.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

UA Indoor and outdoor units do not match

What it means
The indoor and outdoor units are not a combination the system accepts, or the power supply to them is wrong.
Likely cause
Daikin lists: a wrong model combination, an improper power supply, the wrong circuit board fitted, or a faulty board.
What you can safely check

Nothing for the owner to check: this one is for an installer.

When to call an installer
Installer Call your installer: this is a combination or wiring question, usually seen right after installation or a repair.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

A5 Freeze-up protection (cooling) or high-pressure control (heating)

What it means
The indoor coil got too cold while cooling, or the pressure got too high while heating, and the unit stopped to protect itself.
Likely cause
Daikin’s first cause is a clogged air filter on the indoor unit together with air short-circuiting (blown air drawn straight back in); the other is a faulty heat-exchanger thermistor on the indoor unit.
What you can safely check

Air conditioner: do only the checks the maker gives the owner for that code — clean the air filter, clear the air path, switch the power off and on at the plug or circuit breaker. Keep the covers on: refrigerant, wiring and circuit boards are not owner work.

  • Clean the air filters the way Daikin’s guide shows: pull them out, vacuum or wash them in water, soak them for 10 to 15 minutes in lukewarm water if dirty, and dry them in the shade. Daikin recommends cleaning them every 2 weeks.
  • Make sure nothing blocks the air inlet or outlet of the indoor or outdoor unit, so air can flow freely.
When to call an installer
If A5 returns with clean filters and a clear air path, call your installer to check the heat-exchanger thermistor.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

A1 Indoor circuit board fault

What it means
The indoor unit’s circuit board has failed its self-check.
Likely cause
A faulty indoor circuit board, or outside interference such as electrical noise.
What you can safely check

Nothing for the owner to check: this one is for an installer.

When to call an installer
Installer Call your installer: the indoor circuit board is inside the unit.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

A3 Drain level fault

What it means
The water level in the indoor unit’s condensate drain is too high (units with a drain pump).
Likely cause
Daikin lists: a clogged drain or a drain pipe that slopes upward, a faulty drain pump, or a faulty float switch.
What you can safely check

Nothing for the owner to check: this one is for an installer.

When to call an installer
Installer Call your installer: the drain pump and float switch are inside the unit. If water is leaking from the unit, Daikin says to stop operation and contact your dealer.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

A6 Indoor fan motor fault

What it means
The indoor unit’s fan motor is not running as it should.
Likely cause
Broken or disconnected wiring to the fan motor, a faulty fan motor, or a faulty indoor circuit board.
What you can safely check

Nothing for the owner to check: this one is for an installer.

When to call an installer
Installer Call your installer: every cause Daikin lists is inside the indoor unit.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

C4 Indoor coil sensor fault (liquid pipe)

What it means
The temperature sensor (thermistor) on the indoor heat exchanger’s liquid pipe is giving no sensible reading.
Likely cause
A faulty thermistor, a faulty indoor circuit board, or a poor connector contact.
What you can safely check

Nothing for the owner to check: this one is for an installer.

When to call an installer
Installer Call your installer to test and, if needed, replace the sensor.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

C9 Room air sensor fault

What it means
The sensor that measures the air drawn into the indoor unit (the room temperature) has failed.
Likely cause
A faulty suction-air thermistor, a faulty indoor circuit board, or a poor connector contact.
What you can safely check

Nothing for the owner to check: this one is for an installer.

When to call an installer
Installer Call your installer to test and, if needed, replace the sensor.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

E1 Outdoor circuit board fault

What it means
The outdoor unit’s circuit board has failed its self-check.
Likely cause
A faulty outdoor circuit board, or a poor connection on the relay wires between the indoor and outdoor units.
What you can safely check

Nothing for the owner to check: this one is for an installer.

When to call an installer
Installer Call your installer: the outdoor board is behind the outdoor unit’s service panel.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

E5 Compressor locked or overheated

What it means
The inverter compressor has locked or its motor overheated.
Likely cause
Daikin lists: a locked inverter compressor, too high a pressure difference, a faulty inverter board, a wrong compressor wiring connection, or a poor connector contact.
What you can safely check

Nothing for the owner to check: this one is for an installer.

When to call an installer
Installer Call your installer: this is a compressor and refrigerant-circuit fault.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

E6 Compressor overcurrent or lock

What it means
The compressor drew too much current or would not turn.
Likely cause
A faulty compressor or control board — or, right after installation, a stop valve on the outdoor unit that was never opened.
What you can safely check

Nothing for the owner to check: this one is for an installer.

When to call an installer
Installer Call your installer; if the unit is newly installed, mention it, because an unopened stop valve is one of Daikin’s listed causes.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

E7 Outdoor fan motor fault

What it means
The outdoor unit’s fan is not turning as it should.
Likely cause
Daikin lists: a failed fan motor, a missing or poor harness connection between the motor and the board, or something caught in the fan that stops it turning.
What you can safely check

Air conditioner: do only the checks the maker gives the owner for that code — clean the air filter, clear the air path, switch the power off and on at the plug or circuit breaker. Keep the covers on: refrigerant, wiring and circuit boards are not owner work.

  • Look at the outdoor unit from outside and clear anything blocking its air inlet or outlet, such as leaves or snow. Keep your hands and tools out of the fan grille.
When to call an installer
If E7 returns, call your installer: the fan motor and its wiring are inside the outdoor unit.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

EA Cooling/heating changeover fault

What it means
The four-way valve that switches the system between cooling and heating did not switch.
Likely cause
A faulty four-way valve, a shortage of refrigerant gas, a faulty outdoor circuit board, or a faulty thermistor.
What you can safely check

Nothing for the owner to check: this one is for an installer.

When to call an installer
Installer Call your installer: the four-way valve is in the refrigerant circuit.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

F3 Discharge pipe temperature fault

What it means
The temperature of the hot gas leaving the compressor is out of range.
Likely cause
A faulty discharge pipe thermistor, an abnormal discharge temperature, a faulty outdoor control board, or a poor connector contact.
What you can safely check

Nothing for the owner to check: this one is for an installer.

When to call an installer
Installer Call your installer: an abnormal discharge temperature can point to the refrigerant charge.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

H6 Compressor position sensor fault

What it means
The outdoor unit cannot detect the position of the compressor’s rotor, so it cannot run the compressor.
Likely cause
A poor contact on the compressor cable, a faulty compressor, or a faulty outdoor circuit board.
What you can safely check

Nothing for the owner to check: this one is for an installer.

When to call an installer
Installer Call your installer: these are outdoor-unit electrical faults.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

H9 Outdoor air sensor fault

What it means
The thermistor that measures the outdoor air temperature is giving no sensible reading.
Likely cause
A poor thermistor connection, a faulty outdoor circuit board, or a faulty outdoor air thermistor.
What you can safely check

Nothing for the owner to check: this one is for an installer.

When to call an installer
Installer Call your installer to test and, if needed, replace the sensor.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

J3 Discharge pipe sensor fault

What it means
The thermistor on the compressor’s discharge pipe has failed.
Likely cause
A poor thermistor connection, a faulty discharge pipe thermistor, or a faulty outdoor circuit board.
What you can safely check

Nothing for the owner to check: this one is for an installer.

When to call an installer
Installer Call your installer to test and, if needed, replace the sensor.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

J6 Outdoor coil sensor fault

What it means
The thermistor on the outdoor heat exchanger has failed.
Likely cause
A poor thermistor connection, a faulty heat-exchanger thermistor, or a faulty outdoor circuit board.
What you can safely check

Nothing for the owner to check: this one is for an installer.

When to call an installer
Installer Call your installer to test and, if needed, replace the sensor.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

L4 Inverter heat sink too hot

What it means
The cooling fin of the outdoor unit’s inverter has got too hot.
Likely cause
A temperature rise at the fin because hot air is short-circuiting (blown air drawn straight back in), or a faulty fin thermistor.
What you can safely check

Air conditioner: do only the checks the maker gives the owner for that code — clean the air filter, clear the air path, switch the power off and on at the plug or circuit breaker. Keep the covers on: refrigerant, wiring and circuit boards are not owner work.

  • Make sure nothing blocks the outdoor unit’s air inlet or outlet — Daikin’s guide asks owners to remove obstacles so air can flow freely.
When to call an installer
If L4 returns with a clear air path, call your installer to check the fin thermistor.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

L5 Inverter overcurrent

What it means
The inverter saw a sudden overcurrent on its output to the compressor.
Likely cause
Daikin lists: a faulty compressor coil (broken wiring or failed insulation), a compressor that fails to start (mechanical lock), or a faulty inverter board.
What you can safely check

Nothing for the owner to check: this one is for an installer.

When to call an installer
Installer Call your installer: this is a compressor and inverter fault.

Source: Daikin, Daikin Global — After Sales Service: Error Code Search (malfunction codes, Split/Multi Split column) Checked 2026-09-29.

A code that is not listed here

Daikin’s code table has more codes than listed here — nearly 150 across its systems — and its guides say the complete list and the troubleshooting for each code are in the service manual. For any code not listed, Daikin’s instruction to owners is the same: note the code, switch the unit off, and report the code to your installer or dealer.

We list only codes the source below states. If your code is not here, it may belong to a model the source does not cover: your model’s manual is the authority.

Related pages

Source

Every code on this page comes from these pages, published by Daikin and Daikin Europe and read on the date shown. Meanings are written in our own words; nothing is taken from other makes, other models or third-party code sites.