Here are common Daikin Air-to-Water Heat Pump error codes and their meanings:

Sensor Errors:

• A3 – Water flow malfunction or low water pressure

• A5 – High-temperature protection

• C4 – Heat exchanger temperature sensor error

• J3 – Discharge pipe temperature sensor malfunction

• H6 – Indoor fan motor malfunction

Operational Errors:

• E5 – Compressor overload

• E6 – Outdoor unit fan malfunction

• H8 – Outdoor temperature sensor failure

System Error Codes:

• L0 – Inverter PCB malfunction

• L1 – Compressor motor protection error

• L5 – Compressor lock or overcurrent protection

• U0 – Low refrigerant level or insufficient refrigerant

• U2 – Power supply voltage issue

• U4 – Communication error between indoor and outdoor units