Fujitsu · A niche brand in the UK. 120 codes across 2 product families, each taken from the manufacturer’s manuals. Fujitsu technical support ↗
Filter by product family
Type the code on your display or a word from its meaning. Each code opens its own page with what it means, whether it is safe and what you can check.
120 codes
| Code | Meaning | Stops? | Homeowner check? |
|---|---|---|---|
| 9B | Circulator error | Yes | Yes |
| 10 | Communication error with controller board | Partly | Yes |
| 11 | Serial communication error after operation (0) / during operation (1) | Yes | Yes |
| 23 | Different combination of indoor and outdoor unit | Yes | Yes |
| 30 | Flow sensor 1 / flow sensor mixing circuit | Partly | Yes |
| 31 | Cooling flow sensor 1 | Partly | Yes |
| 32 | Command error UART communication | Varies by model | Yes |
| 33 | Flow sensor HP (heat pump flow temperature sensor error) | Partly | Yes |
| 44 | Return sensor HP (heat pump return temperature sensor error) | Partly | Yes |
| 50 | DHW sensor 1 | Partly | Yes |
| 60 | Room sensor 1 | Partly | Yes |
| 62 | Outdoor unit communication error | Yes | Yes |
| 65 | IPM error | Varies by model | Yes |
| 71 | Discharge temperature sensor error | Yes | Yes |
| 72 | Compressor temperature sensor error | Yes | Yes |
| 73 | Heat exchanger temperature sensor error (intermediate / output) | Yes | Yes |
| 74 | Outdoor temperature sensor error | Yes | Yes |
| 76 | Special sensor 1 | Partly | Yes |
| 78 | Expansion valve temperature sensor error | Yes | Yes |
| 79 | Outdoor unit water temperature sensor error | Yes | Yes |
| 83 | BSB, short circuit | Partly | Yes |
| 84 | Current sensor error | Varies by model | Yes |
| 85 | Radio communication error | Partly | Yes |
| 86 | High-pressure sensor error / pressure switch sensor error | Yes | Yes |
| 94 | Trigger detection | Yes | Yes |
| 95 | Detection of compressor rotor position error | Yes | Yes |
| 97 | Outdoor unit fan error | Yes | Yes |
| 98 | Extension module 1 | Partly | Yes |
| 99 | Extension module 2 | Partly | Yes |
| 100 | 2 master clocks on bus | Partly | Yes |
| 102 | Clock without running supply | Partly | Yes |
| 105 | Maintenance message | Partly | Yes |
| 121 | Flow temperature HC1 / mixing circuit too low | Partly | Yes |
| 122 | Flow temperature HC2 / direct circuit too low | Partly | Yes |
| 126 | DHW charge monitoring | Partly | Yes |
| 127 | Legionella temperature (anti-legionella temperature not reached) | Partly | Yes |
| 134 | Heat pump alarm summary | Yes | Yes |
| 138 | No heat pump control sensor | Yes | Yes |
| 146 | Sensor/Control device configuration | Partly | Yes |
| 171 | Alarm contact 1 activated | Partly | Yes |
| 172 | Alarm contact 2 activated | Partly | Yes |
| 174 | Alarm contact 4 active | Partly | Yes |
| 178 | HC1 safety thermostat | Partly | Yes |
| 179 | HC2 safety thermostat | Partly | Yes |
| 201 | Frost alarm | Yes | Yes |
| 212 | Internal comm failure | Partly | Yes |
| 243 | Swimming pool sensor | Partly | Yes |
| 325 | BX/Ext unit: same sensors | Partly | Yes |
| 327 | Ext modules: same functions | Partly | Yes |
| 329 | Ext modules/Mixing group: same functions | Partly | Yes |
| 330-336 | BX1..BX5 / BX21 / BX22 no function | Partly | Yes |
| 356 | Flowmeter | Yes | Yes |
| 357 | Cooling circuit flow temperature not reached | Partly | Yes |
| 359 | No cooling valve Y21 | Partly | Yes |
| 360 | No process reversing valve Y22 | Partly | Yes |
| 364 | Heat pump cooling system error | Partly | Yes |
| 368 | Relay test active | Not stated | Yes |
| 369 | External fault (safety component) | Yes | Yes |
| 370 | Thermodynamic source / outdoor unit fault | Yes | Yes |
| 441 | BX31 no function (2nd zone sensor not configured if 2nd circuit kit) | Yes | Yes |
| 442 | BX24 no function | Yes | Yes |
| 443 | BX33 no function | Yes | Yes |
| 444 | BX34 no function | Yes | Yes |
| 516 | Heat pump missing | Yes | Yes |
| A1 | Discharge temperature protection | Yes | Yes |
| A3 | Compressor temperature protection | Yes | Yes |
| A5 | Abnormal low pressure | Yes | Yes |
| AE | Hydraulic flow error | Yes | Yes |
| G1 | Outdoor temperature sensor faulty | Not stated | Yes |
| G2 | External safety input | Not stated | Yes |
| G6 | Outdoor unit error | Not stated | Yes |
| G7 | Flow temperature sensor faulty | Not stated | Yes |
| G8 | Return temperature sensor faulty | Not stated | Yes |
| G9 | Water pressure sensor faulty | Not stated | Yes |
| G11 | Water pressure too low | Not stated | Yes |
| G12 | Water pressure too high | Not stated | Yes |
| G14 | System circulator faulty | Not stated | Yes |
| G15 | System circulator faulty | Not stated | Yes |
| G16 | Directional valve faulty | Not stated | Yes |
| G18 | Circuit 2 temperature sensor faulty | Not stated | Yes |
| G22 | DHW temperature sensor faulty | Not stated | Yes |
| G27 | Abnormally long anti-legionella cycles | Not stated | Yes |
| G29 | Outdoor unit communication lost | Not stated | Yes |
| G30 | Zone 1 room thermostat communication lost | Not stated | Yes |
| G31 | Zone 2 room thermostat communication lost | Not stated | Yes |
| G32 | Zone 3 room thermostat communication lost | Not stated | Yes |
| G45 | Loss of remote outdoor temperature sensor | Not stated | Yes |
| G46 | System circulator communication lost | Not stated | Yes |
| NO-CONNECTION | No connection (room sensor polarity) | Yes | Yes |
| OU-11 | Serial communication error between hydraulic unit and outdoor unit (R32: after operation / during operation) | Yes | Yes |
| OU-23 | Connection forbidden (series error) / different combination of indoor and outdoor units | Yes | Yes |
| OU-31 | Indoor (hydraulic) unit power supply abnormal | Yes | Yes |
| OU-32 | Serial (UART) communication error between controller/interface PCBs | Yes | Yes |
| OU-41 | Heat pump capacity signal error (open or short) | Yes | Yes |
| OU-42 | Hydraulic unit heat-exchange thermistor error | Yes | Yes |
| OU-61 | Outdoor unit power supply abnormal | Yes | Yes |
| OU-62 | Outdoor unit main PCB error | Yes | Yes |
| OU-63 | Inverter error | Yes | Yes |
| OU-64 | Active filter error (1ph) / P.F.C. error (3ph) | Yes | Yes |
| OU-65 | Outdoor unit IPM error (R32 also: IPM board temperature error) | Yes | Yes |
| OU-67 | Outdoor unit power short interruption error (protective operation) | Yes | Yes |
| OU-68 | Outdoor unit magnetic relay error | Yes | Yes |
| OU-71 | Discharge thermistor error | Yes | Yes |
| OU-72 | Compressor thermistor error | Yes | Yes |
| OU-73 | Heat-exchange thermistor (outlet / intermediate) error | Yes | Yes |
| OU-74 | Outdoor (air) thermistor error | Yes | Yes |
| OU-77 | Outdoor unit heat sink temperature thermistor error | Yes | Yes |
| OU-78 | Expansion valve thermistor error | Yes | Yes |
| OU-84 | Current sensor error | Yes | Yes |
| OU-86 | Pressure sensor error / pressure switch error | Yes | Yes |
| OU-94 | Current trip (permanent stoppage) / trigger detection | Yes | Yes |
| OU-95 | Detection of compressor position error / compressor start-up error (permanent stoppage) | Yes | Yes |
| OU-97 | Outdoor unit fan (1) motor error | Yes | Yes |
| OU-98 | Outdoor unit fan 2 motor error | Yes | Yes |
| OU-A1 | Discharge temperature protection (permanent stoppage) | Yes | Yes |
| OU-A3 | Compressor temperature protection (permanent stoppage) | Yes | Yes |
| OU-A4 | Outdoor unit pressure error | Yes | Yes |
| OU-A5 | Low pressure abnormal | Yes | Yes |
| OU-A9 | Current overload error | Yes | Yes |
| OU-AC | Outdoor unit radiator (heat sink) temperature error | Yes | Yes |