Hitachi · An established brand in the UK. 125 codes across 6 product families, each taken from the manufacturer’s manuals. Hitachi technical support ↗
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125 codes
| Code | Meaning | Stops? | Homeowner check? |
|---|---|---|---|
| 2 | Activation of protection device (high pressure switch) | Yes | Yes |
| 02-13 | Activation of freeze protection control (water outlet) | Yes | Yes |
| 02-91 | Excessively high discharge gas temperature | Yes | Yes |
| 02-e1 | Excessively low pressure difference | Yes | Yes |
| 02-g1 | Excessively low temperature of heat exchanger refrigerant inlet | Yes | Yes |
| 02-H1 | Activation of high pressure switch | Yes | Yes |
| 02-t1 | Excessively low suction gas temperature | Yes | Yes |
| 3 | Transmission alarm - outdoor unit not detected (abnormal transmission between indoor and outdoor units) | Yes | Yes |
| 4 | Abnormal transmission between inverter PCB and RAS unit PCB | Yes | Yes |
| 04 | Abnormal transmission between inverter PCB and main PCB | Yes | Yes |
| 5 | Reception of abnormal operation code for detection of power source phase | Yes | Yes |
| 05 | Abnormality of power supply phase | Yes | Yes |
| 5b | Activation of over current protection (outdoor fan) | Yes | Yes |
| 5c | Abnormality in current detection circuit (outdoor fan) | Yes | Yes |
| 5P | No feedback signal from water pump | Yes | Yes |
| 6 | Excessively low or excessively high voltage for the inverter | Yes | Yes |
| 06 | Excessively low or excessively high voltage for the inverter | Yes | Yes |
| 7 | Decrease in discharge gas superheat | Yes | Yes |
| 8 | Excessively high discharge gas temperature at the top of the compressor | Yes | Yes |
| 10 | Domestic hot water tank top temperature thermistor (THMDHWT2) anomaly | Yes | Yes |
| 11 | Water inlet thermistor anomaly (THMwi) | Yes | Yes |
| 12 | Water outlet thermistor anomaly (THMwo) | Yes | Yes |
| 13 | Indoor liquid pipe refrigerant temperature thermistor anomaly (THML) | Yes | Yes |
| 14 | Indoor gas pipe refrigerant temperature thermistor anomaly (THMg) | Yes | Yes |
| 15 | Water circuit 2 (mixing circuit) temperature thermistor anomaly (THMwo2) | Yes | Yes |
| 16 | Domestic hot water temperature thermistor anomaly (THMdhwt) | Yes | Yes |
| 17 | Auxiliary temperature sensor 2 thermistor anomaly (THMaux2) | Yes | Yes |
| 18 | Auxiliary temperature sensor 1 thermistor anomaly (THMaux1) | Yes | Yes |
| 19 | Water plate heat exchanger pipe thermistor anomaly (THMwohp) | Yes | Yes |
| 20 | Thermistor for discharge gas temperature (THM9, compressor-top thermistor) anomaly | Yes | Yes |
| 21 | Abnormality of high pressure sensor | Yes | Yes |
| 22 | Thermistor for outdoor ambient temperature (THM7) anomaly | Yes | Yes |
| 23 | Failure of discharge gas temperature thermistor (open/short) | Yes | Yes |
| 24 | Thermistor for evaporation / condensation temperature (THM8) anomaly | Yes | Yes |
| 25 | Auxiliary sensor 3 thermistor anomaly (THMaux3) | Yes | Yes |
| 26 | Water pressure sensor (WPS) anomaly | Yes | Yes |
| 27 | Economizer thermistor abnormality | Yes | Yes |
| 28 | Failure of suction gas thermistor | Yes | Yes |
| 29 | Low pressure sensor abnormality | Yes | Yes |
| 30 | Incorrect PCB setting | Yes | Yes |
| 31 | Incorrect capacity setting or combined capacity between indoor and outdoor units | Yes | Yes |
| 35 | Incorrect indoor unit number setting | Yes | Yes |
| 36 | Indoor unit combination error | Yes | Yes |
| 38 | Anomaly at picking-up circuit for protection (outdoor unit) | Yes | Yes |
| 40 | Incorrect unit controller setting | Yes | Yes |
| 41 | Cooling overload (outdoor) | Yes | Yes |
| 42 | Pressure ratio increase abnormality | Yes | Yes |
| 43 | Pressure ratio decrease abnormality | Yes | Yes |
| 44 | Low pressure increase abnormality | Yes | Yes |
| 45 | Activation of the safety device from excessively high discharge pressure | Yes | Yes |
| 47 | Activation of the safety device from excessively low suction pressure (protection from vacuum operation) | Yes | Yes |
| 48 | Activation of overcurrent protection | Yes | Yes |
| 51 | Abnormal operation of the current sensor | Yes | Yes |
| 52 | Activation of protection for inverter instantaneous overcurrent | Yes | Yes |
| 53 | Inverter fin temperature increase / protection of the inverter PCB | Yes | Yes |
| 54 | Abnormality of inverter fin temperature | Yes | Yes |
| 55 | Abnormality of inverter module (inverter non-operation) | Yes | Yes |
| 57 | Fan motor protection - abnormality of fan motor protection (DC fan motor) | Yes | Yes |
| 59 | Inverter fin temperature thermistor abnormality | Yes | Yes |
| 61 | No cascade messages - unit configured for YUTAKI Cascade Controller but no messages received for 180 s or since start | Yes | Yes |
| 62 | Central mismatch - Cascade Controller configured but central messages received, or central control configured but Cascade Controller messages received | Yes | Yes |
| 63 | Transmission error between central controller and indoor unit | Yes | Yes |
| 70 | Hydraulic alarm - low water flow and water pump malfunction (retry code P70) | Yes | Yes |
| 71 | Water pump feedback alarm | Yes | Yes |
| 72 | Thermostat heater alarm - high temperature detected in the electric heater | Yes | Yes |
| 73 | Mixing over-temperature limit protection for mixed circuit (circuit 2) | Yes | Yes |
| 74 | Unit over-temperature limit protection (retry code P74) | Yes | Yes |
| 75 | Freeze protection by cold water inlet/outlet temperature detection | Yes | Yes |
| 76 | Freeze protection stop by indoor liquid temperature thermistor | Yes | Yes |
| 77 | Receiver communication failure (intelligent wireless receiver / OpenTherm / H-Link) | Yes | Yes |
| 78 | RF communication failure (intelligent thermostat accessory) | Yes | Yes |
| 79 | Unit capacity setting error | Yes | Yes |
| 80 | Unit controller H-Link (RCS) transmission error between indoor unit and unit controller (PC-ARFH2E) | Yes | Yes |
| 81 | Momentary power interruption or low voltage detected (retry code P81) | Yes | Yes |
| 83 | Hydraulic alarm - low water pressure (retry code P83) | Yes | Yes |
| 84 | High water pressure | Yes | Yes |
| 100 | Compressor protection (shown as EE on outdoor unit) - alarms 02, 07, 08, 45, 47 three times within 6 hours | Yes | Yes |
| 101 | Activation of high pressure switch (S80 R134a stage) | Yes | Yes |
| 102 | Activation of protection control for excessively high pressure (retry code P12) | Yes | Yes |
| 104 | Activation of low pressure protection control (retry code P06) | Yes | Yes |
| 105 | Excessively low pressure difference (retry code P11) | Yes | Yes |
| 106 | Excessively high discharge gas temperature (S80 R134a stage) | Yes | Yes |
| 129 | Failure of discharge gas pressure sensor | Yes | Yes |
| 130 | Failure of suction gas pressure sensor | Yes | Yes |
| 132 | Transmission error between inverter PCB and main PCB (S80) | Yes | Yes |
| 134 | Power supply phase anomaly - reverse/open phase (S80) | Yes | Yes |
| 135 | Incorrect PCB setting (S80) | Yes | Yes |
| 151 | Excessively low or high voltage for the inverter (S80) | Yes | Yes |
| 152 | Abnormal operation of the current sensor (S80) | Yes | Yes |
| 153 | Activation of protection for inverter instantaneous overcurrent (S80) | Yes | Yes |
| 154 | Transistor module protection activation (S80) | Yes | Yes |
| 155 | Increase in the inverter fin temperature or abnormality (S80) | Yes | Yes |
| 156 | Inverter non-operation (S80) | Yes | Yes |
| 157 | Other inverter abnormalities (S80) | Yes | Yes |
| 202 | Wrong settings of PC-ARFH2E unit controller | Yes | Yes |
| 203 | Slave (sub) PC-ARFH2E stops answering to master PC-ARFH2E | Yes | Yes |
| 204 | Indoor unit stops answering to master PC-ARFH2E | Yes | Yes |
| 205 | Central alarm - no central message | Yes | Yes |
| b0 | Incorrect setting of unit model | Yes | Yes |
| b1 | Incorrect setting of address or refrigerant cycle number | Yes | Yes |
| b5 | Incorrect setting of indoor unit number for H-LINK type | Yes | Yes |
| EE | Compressor protection - alarms 02, 07, 08, 45 or 47 occurred three times within 6 hours | Yes | Yes |
| F01 | No outside temperature sensor, short circuit or out of range | Partly | Yes |
| F02 | No DHW water temperature sensor, short circuit or out of range | Partly | Yes |
| F03 | No HC1 supply water temperature sensor, short circuit or out of range (mixing circuit only) | Partly | Yes |
| F04 | No HC2 supply water temperature sensor, short circuit or out of range (mixing circuit only) | Partly | Yes |
| F05 | No boiler water temperature sensor or sensor failure/out of range | Partly | Yes |
| F06 | No system supply water temperature sensor, short circuit or out of range | Partly | Yes |
| F07 | OpenTherm communication failure | Partly | Yes |
| F08 | Heat pump connection fault | Partly | Yes |
| F09 | Heat pump communications fault (Modbus) | Partly | Yes |
| F10 | Mixing over-temperature limit protection HC1 | Partly | Yes |
| F11 | Mixing over-temperature limit protection HC2 | Partly | Yes |
| F12 | Heat pump fault | Partly | Yes |
| F13 | RF communication failure | Partly | Yes |
| F14 | Heat pump maximum inlet temperature protection active | Partly | Yes |
| F15 | DHW anti-legionella failure | Partly | Yes |
| F16 | HP individual alarm | Partly | Yes |
| F17 | HP unit alarm | Partly | Yes |
| FA | Failure of fan motor (MF1) | Yes | Yes |
| Fb | Failure of fan motor (MF2) | Yes | Yes |
| pU-flashing | Excessively high water temperature (compressor stop) - pU flickering | Yes | Yes |
| YCC-03 | Lost communication with all slave YUTAKI units (YUTAKI Cascade Controller) | Partly | Yes |
| YCC-21X | Slave unit alarm - module X in alarm state or cascade controller lost communication with module X | Partly | Yes |
| YCC-60 | Slave unit alarm - all slave units in alarm state or no communication (YUTAKI Cascade Controller) | Partly | Yes |