Aircon Error Codes · Singapore · Updated June 2026
Daikin Aircon Error Codes
When a Daikin split or multi-split unit detects a fault it stops and flashes the operation/timer LED on the indoor unit; you can read the two-character error code on the wireless remote by holding the TIMER CANCEL button for about 5 seconds (or via the inspection mode on a wired controller). Each code points to a specific area — the indoor or outdoor unit, refrigerant, a sensor, the fan motor, or the control board — so it tells you roughly where the problem is before a technician arrives.
Daikin error codes explained
What each code means, the likely cause, and what to do — with the fix and typical cost.
U0 — Refrigerant shortage detected by the system.
Gas top-up from $80Likely cause: Low or leaking refrigerant, or clogged/restricted refrigerant piping (sometimes a faulty low-pressure sensor or thermistor).
What to do: Treat as a possible gas leak; switch the unit off and book a technician to leak-test and top up the refrigerant.
U2 — Power supply fault or instantaneous power failure.
Aircon repair from $50Likely cause: Abnormal supply voltage, a brief power interruption, or faulty main-circuit wiring.
What to do: Power the unit off at the isolator for a minute and restart; if it returns, have a technician check the supply.
U4 — Communication failure between the indoor and outdoor units.
Aircon repair from $50Likely cause: Damaged, loose or wrongly connected interconnecting signal wiring, outdoor power off, or a faulty PCB.
What to do: Check the outdoor unit has power; the wiring/PCB diagnosis needs a technician.
U5 — Communication failure between the indoor unit and the remote controller.
Aircon repair from $50Likely cause: Faulty controller wiring, two remotes both set as main, electrical noise, or a faulty controller/indoor PCB.
What to do: Try a power reset; if the code persists, have a technician check the controller and wiring.
UA — Improper combination or field-setting error between indoor and outdoor units.
Aircon repair from $50Likely cause: Mismatched or wrong-quantity indoor/outdoor models, incorrect field setting, or a PCB not configured after replacement.
What to do: This is an installation/configuration issue for a technician; no DIY fix.
A1 — Indoor unit printed circuit board (PCB) fault.
Aircon repair from $50Likely cause: Defective indoor PCB or external interference such as electrical noise.
What to do: Try a power reset; if it recurs the indoor control board needs a technician.
A3 — Drain (condensate) water level control fault.
Chemical wash from $110Likely cause: Clogged or wrongly sloped drain, faulty drain pump, or a stuck float switch.
What to do: Often a blocked drain that clears with servicing; book a chemical wash / drain clearing.
A5 — Freeze-up protection in cooling (or high-pressure control in heating) activated.
Chemical wash from $110Likely cause: Dirty/clogged indoor filter or coil restricting airflow, or a faulty indoor coil thermistor.
What to do: Clean the filter; if it persists the coil likely needs a chemical wash.
A6 — Indoor fan motor fault.
Aircon repair from $50Likely cause: Locked, overloaded or faulty fan motor, broken wiring/connector, or a faulty indoor PCB.
What to do: Switch off and call a technician to test the fan motor and wiring.
C4 — Indoor heat-exchanger liquid-pipe thermistor (sensor) fault.
Aircon repair from $50Likely cause: Open or short-circuited liquid-pipe sensor, loose connector, or a faulty indoor PCB.
What to do: Sensor replacement is needed; book a technician.
C9 — Indoor suction (return) air thermistor (sensor) fault.
Aircon repair from $50Likely cause: Open or short-circuited return-air sensor, loose connector, or a faulty indoor PCB.
What to do: Sensor replacement is needed; book a technician.
E1 — Outdoor unit printed circuit board (PCB) fault.
Aircon repair from $50Likely cause: Defective outdoor PCB or faulty indoor/outdoor relay wiring.
What to do: The outdoor control board needs a technician; no DIY fix.
E3 — High-pressure switch activated (abnormally high refrigerant pressure).
Chemical wash from $110Likely cause: Dirty outdoor heat exchanger, clogged refrigerant piping, or a faulty high-pressure switch.
What to do: A dirty outdoor coil is a common cause and is cleared by servicing; book a chemical wash and have a technician verify.
E5 — Inverter compressor overload/overheat or motor lock.
Aircon repair from $50Likely cause: Compressor locked or overheating, high differential pressure, or a faulty inverter PCB/wiring.
What to do: Switch off and call a technician; this is a serious compressor/inverter fault.
E6 — Compressor overcurrent or locked compressor.
Aircon repair from $50Likely cause: Faulty compressor, a closed stop valve, or a faulty control PCB.
What to do: Switch off and call a technician to diagnose the compressor.
E7 — Outdoor fan motor fault.
Aircon repair from $50Likely cause: Failed fan motor, broken/loose motor wiring, or the fan blocked by debris.
What to do: Switch off and call a technician to test the outdoor fan motor and wiring.
F3 — Abnormally high compressor discharge-pipe temperature.
Aircon repair from $50Likely cause: Insufficient refrigerant or clogged piping, or a faulty discharge-pipe thermistor.
What to do: Switch off and call a technician to check refrigerant charge and the sensor.
H6 — Compressor position-detection fault.
Aircon repair from $50Likely cause: Faulty compressor wiring contact, a faulty compressor, or a faulty outdoor PCB.
What to do: Needs a technician to diagnose the compressor/inverter system.
H9 — Outdoor air thermistor (ambient sensor) fault.
Aircon repair from $50Likely cause: Open or short-circuited outdoor air sensor, loose connector, or a faulty outdoor PCB.
What to do: Sensor replacement is needed; book a technician.
Code not listed, or not sure?
Daikin error codes can vary slightly by model and series. If your code isn’t here — or you’d rather not guess — send us a photo of the display on WhatsApp and we’ll tell you what it means and what it’ll cost to fix. We diagnose on-site, quote before any work, and can usually fix it the same day. Servicing across Singapore from $45.
Error codes for other brands
Or browse common aircon problems and fixes.
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