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Grant Fault Codes
Select a fault code to see its meaning, common causes and how to fix it.
- 740 Fault code 740 appears on the display or terminal PCB of certain Grant heat pump models and is believed to relate to an… Read more →
- A0 The A0 fault code on Grant heat pumps indicates a DC voltage error within the inverter's internal DC bus — the… Read more →
- A1 The A1 fault code on the Grant Aerona and Aerona³ heat pump signals a discharge temperature error. This means the… Read more →
- A2 A2 on a Grant Aerona³ heat pump is a DC current detection error: the inverter's current-measurement circuit on the main… Read more →
- A3 The A3 fault code on the Grant Aerona³ heat pump indicates a Current Transformer (CT) disconnection fault. The CT… Read more →
- A4 A4 on a Grant Aerona³ heat pump is an AC current detection error — the unit's protection against excessive current draw… Read more →
- A5 The A5 code appears on the Grant Aerona³ remote controller and terminal PCB display when the heat pump's control system… Read more →
- A6 A6 on a Grant Aerona³ heat pump reports a suction temperature sensor error: the thermistor measuring refrigerant… Read more →
- A7 A7 on a Grant Aerona³ heat pump reports a defrost temperature sensor error: the thermistor on the outdoor coil that… Read more →
- A8 The A8 fault code on the Grant Aerona³ heat pump indicates that the outdoor ambient air temperature sensor (commonly… Read more →
- C1 The C1 code on the Grant Aerona³ indicates a fault detected in the compressor discharge temperature sensor — the… Read more →
- C2 The C2 code on a Grant Aerona³ heat pump indicates a fault within the compressor protection system, most likely… Read more →
- C3 The C3 fault code on the Grant Aerona³ air source heat pump indicates that the unit has detected an abnormally high… Read more →
- C4 The C4 fault code on the Grant Aerona³ heat pump indicates a problem with the outgoing (flow) water temperature sensor… Read more →
- C5 C5 on a Grant Aerona³ heat pump reports a main PCB sensor error: a sensor input on the main (inverter) circuit board… Read more →
- C6 The C6 code on a Grant Aerona³ heat pump indicates that the unit has detected a fan failure or an air pressure switch… Read more →
- C7 C7 on a Grant Aerona³ heat pump is a controller PCB serial error: the digital communication link between the unit's… Read more →
- C8 C8 on a Grant Aerona³ heat pump reports a main PCB error — the inverter board has failed an internal check that does… Read more →
- E4 E4 on a Grant Aerona³ heat pump reports an outgoing (flow) water temperature sensor error: the thermistor measuring the… Read more →
- E5 E5 on a Grant Aerona³ heat pump reports a return water temperature sensor error: the thermistor measuring the water… Read more →
- E8 The E8 fault code on the Grant Aerona³ air source heat pump indicates that the unit has entered a protective shutdown… Read more →
- F5 The F5 code appears on your Grant Aerona³ remote controller when the heat pump's control system has detected a problem… Read more →
- FU FU on a Grant Aerona³ heat pump (the 13kW and 17kW HPID13R32/HPID17R32 models) is a pump error: the circulating pump… Read more →
- L0 L0 on a Grant Aerona³ heat pump is an EEPROM error on the controller: the non-volatile memory holding the controller… Read more →
- L1 The L1 fault code on the Grant Aerona³ heat pump indicates a safety lockout triggered by the system detecting a problem… Read more →
- L2 The L2 fault code on the Grant Aerona³ air source heat pump indicates that the control system has detected a problem… Read more →
- L3 The L3 fault code on the Grant Aerona³ air source heat pump indicates a problem with the outdoor ambient air… Read more →
- L4 L4 on a Grant Aerona³ heat pump reports a mix water temperature sensor error: the thermistor measuring temperature at a… Read more →
- L5 L5 on a Grant Aerona³ heat pump reports a humidity sensor error: a humidity measurement the controller has been… Read more →
- P1 P1 on a Grant Aerona³ heat pump is a pump error: the controller has detected that water is not circulating properly… Read more →
- P3 P3 on a Grant Aerona³ heat pump (the 13kW and 17kW HPID13R32/HPID17R32 models) reports a high pressure switch error:… Read more →
- U1 U1 on a Grant Aerona³ heat pump (the 13kW and 17kW HPID13R32/HPID17R32 models) is compressor overheat protection: the… Read more →