Grant Aerona R32 fault codes

26 codes from the Grant manual for the Aerona R32 heat pump. Pick one for what it means, the likely causes and where to start.

Code	What it means
740	Remote controller communication error
A0	DC voltage error
A1	Discharge temperature error
A2	Protective action against excess current DC current detection
A4	Protective action against excess current AC current detection
A5	Abnormal revolution of compressor
A6	Suction temperature sensor error
A7	Auto defrost temp sensor error
A8	Discharge temp. sensor error
C1	Upper fan motor error (HPID13R32 & HPID17R32)
C2	Outdoor temp. sensor error
C3	Lower fan motor error (HPID13R32 & HPID17R32) / fan motor error (HPID6R32 & HPID10R32)
C4	Rise of temperature (above 110°C) of main PCB
C7	Controller PCB serial error
C8	Main PCB error
E4	Outgoing water temp. sensor error
E5	Return water temp. sensor error
E8	Remote controller communication error
F5	Main PCB communication error
L0	EEPROM error
L1	DHW temperature sensor error
L2	Outdoor temperature sensor error
L3	Thermal store temperature sensor error
L4	Mix water temperature sensor error
P1	Pump error
U1	Compressor overheat protection relay operation (HPID13R32 & HPID17R32)