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Daikin FTX / FVXS / FDMQ with RXL outdoor Error Codes
Daikin residential splits share most of these two-character codes, but descriptions and causes vary by series. Check the service manual for your model.
| Code | Meaning | What to check |
|---|---|---|
| 00 | Normal. | |
| U0 | Refrigerant shortage. | Leak search, especially flare joints; check service valves are fully open. How to fix → |
| U2 | Low-voltage or over-voltage detection. | Supply voltage under load, loose terminals, DC bus. How to fix → |
| U4 | Signal transmission error between indoor and outdoor unit. | Interconnect wiring (terminals 1-2-3), splices, polarity, ground. How to fix → |
| U5 | Signal transmission error between indoor unit and remote controller. | Wired remote wiring and connections. |
| U7 | Signal transmission error on outdoor unit PCB. | Outdoor PCB connections; replace the board if they're good. |
| U8 | Signal transmission error between main and sub remote controllers. | Remote controller wiring and main/sub setting. |
| UA | Unspecified voltage between indoor and outdoor unit (mismatched units). | Confirm the indoor and outdoor models are an approved match. How to fix → |
| A1 | Indoor unit PCB abnormality. | Indoor control board. |
| A3 | Drain level control system abnormality. | Drain pump, float switch, plugged drain. |
| A5 | Freeze-up protection control / heating peak-cut control. | Airflow (filter, coil, fan) and refrigerant charge. |
| A6 | Indoor fan motor (DC motor) or related abnormality. | Fan motor, connector, blower wheel binding. |
| A8 | Indoor fan PCB abnormality. | Fan control board. |
| AF | Humidifier or related abnormality. | |
| C4 | Indoor heat exchanger thermistor or related abnormality. | Measure the thermistor against its resistance chart; check connector. How to fix → |
| C9 | Room temperature thermistor or related abnormality. | Measure the thermistor; check connector. How to fix → |
| CJ | Remote controller thermistor abnormality. | How to fix → |
| E1 | Outdoor unit PCB abnormality. | Outdoor control board. |
| E5 | OL activation (compressor overload). | Refrigerant charge, restrictions, compressor, outdoor airflow. |
| E6 | Compressor lock. | Compressor windings and wiring, inverter output. How to fix → |
| E7 | DC fan lock (outdoor fan). | Outdoor fan motor, blade obstruction, connector. |
| E8 | Input overcurrent detection. | Supply voltage, compressor, refrigerant overcharge. How to fix → |
| EA | Four-way valve abnormality. | Reversing valve coil and operation, thermistors. |
| F3 | Discharge pipe temperature control. | Low charge or restriction (high discharge temp). How to fix → |
| F6 | High pressure control in cooling. | Dirty outdoor coil, fan, overcharge, recirculating air. |
| F8 | System shutdown due to temperature abnormality in the compressor. | |
| H0 | Compressor system sensor abnormality. | How to fix → |
| H6 | Position sensor abnormality. | Compressor wiring and inverter board. How to fix → |
| H9 | Outdoor temperature thermistor or related abnormality. | Measure the thermistor; check connector. How to fix → |
| J3 | Discharge pipe thermistor or related abnormality. | Measure the thermistor; check connector. How to fix → |
| J6 | Outdoor heat exchanger thermistor or related abnormality. | Measure the thermistor; check connector. How to fix → |
| L3 | Electrical box temperature rise. | |
| L4 | Radiation fin (heat sink) temperature rise. | Outdoor airflow, heat sink contact, fan. How to fix → |
| L5 | Output overcurrent detection. | Compressor, inverter output, refrigerant system. How to fix → |
| P4 | Radiation fin thermistor or related abnormality. | How to fix → |
How to read the codes
- On many Daikin wireless remotes: point the remote at the unit and hold the CANCEL (or TEMP) button about 5 seconds until '00' shows. Press it repeatedly; the code shown when the unit gives a long beep is the error.
- A short beep twice means the displayed code doesn't match; '00' with a long beep means normal.
- Codes starting with U are communication or power, A and C are indoor, E, F, H, J, L and P are outdoor.
Codes point to a circuit, not a part. Test before replacing boards or sensors. Inverter boards hold a dangerous charge after power-off; wait and verify DC bus voltage is gone before touching them. Refrigerant work requires EPA 608 certification.
Source: Daikin Service Manual SiUS091601ED (FTX/FVXS/FDMQ with RXL), Error Codes and Description. The "meaning" column follows the manufacturer's wording; "what to check" is our field summary. Always go by the label on the furnace you're working on.
Related
- Mini-split communication error troubleshooting
- Mini-split flare connections (the usual leak point)
- Look up any mini-split code
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