Daikin Mini Split Error Codes Explained (2026)
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Daikin error codes — quick lookup
Common Daikin mini-split & heat pump codes. Codes can vary by model — confirm against your unit's Daikin manual.
| Code | What it means | What to do |
|---|---|---|
U0 | Low refrigerant / refrigerant shortage | Likely a leak — needs a certified technician |
U2 | Power-supply voltage abnormal (over/under-voltage) | Check breaker & supply voltage; if it recurs, call a pro |
U4 / UF | Communication fault between indoor & outdoor units (often wiring) | Power-cycle; inspect interconnecting wiring; persists → tech |
A1 | Indoor unit PCB (control board) fault | Power-cycle once; if it returns, call a pro |
A5 | High-pressure control / freeze-up protection | Check airflow — clean a dirty filter/coil; restore airflow |
A6 | Indoor fan motor fault or obstruction | Clear obstructions; if it returns, call a pro |
C4 / C9 | Heat-exchanger / suction-air thermistor (sensor) fault | Technician — sensor replacement |
E1 | Outdoor unit PCB (control board) fault | Technician |
E5 | Compressor motor overload / lock (OL) | Power off — technician (compressor) |
E6 | Compressor start fault / locked rotor | Technician |
E7 | Outdoor fan motor fault | Clear debris around the outdoor unit; persists → tech |
F3 | Discharge-pipe temperature too high | Power off — technician (airflow/refrigerant) |
H6 | Compressor position-sensor detection fault | Technician |
L5 | Inverter compressor over-current | Technician |
P4 | Discharge-pipe thermistor (sensor) fault | Technician |
Daikin mini-split and heat pump systems show a two-character error code on the indoor unit’s display, or signal it by blinking the operation and timer LEDs, when a fault is detected. The first character is a letter that points to the affected area — A and C codes relate to the indoor unit and its sensors, E codes to the outdoor unit and compressor, F, H, L and P codes to the refrigerant system and compressor, and U codes to system-level problems such as communication, power supply, or low refrigerant. The second character narrows down the specific fault. Use the quick-answer table above to find your exact Daikin error code, what it means, and the safe first step. Some codes clear after a simple power cycle; others — especially compressor, refrigerant, and sensor faults — require a licensed technician. Always confirm the meaning against the code list in your model’s Daikin manual, as codes can vary slightly by unit.
How to read a Daikin error code
Where the code appears depends on your unit type:
- Wall-mounted units: the code shows on the indoor unit’s display, or the unit flashes the operation and timer LEDs in a pattern. Pressing the Cancel/Timer button on the remote often prompts the unit to display the stored code.
- Ducted and concealed units: the code is usually reported through the wired controller (thermostat).
What the first letter tells you
| Letter | Area of the system |
|---|---|
| A | Indoor unit (control board, protection) |
| C | Sensors / thermistors |
| E | Outdoor unit and compressor |
| F · H · L · P | Refrigerant circuit & compressor |
| U | System-level: communication, power, refrigerant charge |
What to do first
For non-safety codes (communication, fan, airflow, sensor reads), a single power cycle resolves many transient faults:
- Turn the unit off with the remote.
- Switch off the circuit breaker feeding the system for about one minute.
- Restore power and let the unit restart.
If the same code returns, stop — a repeating code means the underlying problem is still present and needs diagnosis. Do not keep resetting compressor or refrigerant codes.
Sources
- Daikin published error-code and diagnostics documentation (operation and installation manuals; service/troubleshooting references). Look up the exact code list for your model number on Daikin’s official documentation.
Trademark note: “Daikin” is a trademark of Daikin Industries, Ltd. This page is an independent homeowner resource and is not affiliated with, authorized by, or endorsed by Daikin. Brand and code references are used factually for identification and troubleshooting only.
Frequently asked questions
How do I find the error code on my Daikin mini split?
On most wall-mounted Daikin indoor units the code appears on the small display, or the unit signals it by blinking the operation and timer LEDs. Pressing the "Cancel" (timer) button on the remote can prompt the unit to show the stored code. Concealed and ducted units typically report the code through their wired controller. Always cross-check the reading against the error-code list in your model's manual.
What does the Daikin U4 error code mean?
U4 (sometimes shown with UF) indicates a communication fault between the indoor and outdoor units. It is commonly caused by interconnecting wiring that is loose, miswired, or damaged, or by a control-board fault. Turn the system off at the breaker for about a minute and restore power; if U4 returns, have a technician inspect the wiring and boards.
Can I reset a Daikin error code myself?
You can safely clear many codes with a power cycle: turn the unit off at the remote, switch off its circuit breaker for about one minute, then restore power. This is fine for one attempt. If the same code returns, stop resetting and have it diagnosed — a repeating code means the underlying fault is still present.
When should I call a professional for a Daikin error code?
Call a licensed HVAC technician for any code involving the compressor, refrigerant circuit, or high-voltage components (for example E5, E6, F3, H6, L5, P4, and U0), and for any code that returns after a single power cycle. Refrigerant handling requires EPA Section 608 certification.