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 →
A3 The A3 fault code on the Grant Aerona³ heat pump indicates a Current Transformer (CT) disconnection fault. The CT… 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 →
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 →
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 →
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 →
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 →