Fault Codes

Listed below are the common Daikin fault codes as described by the boiler manufacturer along with a possible cause.

D2CND Combi Gas Boiler Error Codes

Fault CodePossible Cause
10-64 Gas valve circuit error, try resetting the boiler
10-65 Gas valve current fault, try resetting the boiler
11-64 Ignition error – possible fault with valve on the gas line due to it being open. Try resetting the boiler after the third unsuccessful ignition
11-65 Flame stabilisation error – wait for the boiler ignition trial
11-66 Flame Signal loss in safety time – try to reset the boiler after 3rd unsuccessful ignition
11-67 Flame loss during operation. This is a temporary error, wait for the boiler to re-ignite.
12-64 Ion control deviation is too big – try resetting the boiler
12-65 Ignition scott actuators error – try resetting the boiler
12-66 Ion base value lower than the upper factory limit, try resetting the boiler
12-67 Ion base value exceeds the upper factory limit – try resetting the boiler
12-68 Ion base value differs from the previous value – try resetting the boiler
12-69 Offset adaptation at limit
13-64 / 13-65 Fan speed error – try resetting the boiler
16-64 Flue temperature signals overheating, the flue gas discharge path needs checking, Try resetting the boiler
1J-64 High limit thermostat signalising overheating. Check the valve of the radiators in the heating, check if the Combi boiler water pressure is low, if it is then the heating circuit needs filling with water
80-01 Return temperature sensor error – reset the boiler
81-01 Flow temperature sensor error – try resetting the boiler
81-65 Domestic hot water (DHW) temperature sensor error. The boiler will continue in operation but solar sensor has an error 
8A-46 Freeze protection – the boiler won’t operate if flow temperature sensor reads a value that is less than 1°c
8H-65 Flow temperature steep rise – the radiator valves may not be open enough to circulate water
E1-64 Flame detected before burner operation – try resetting the boiler
E1-65 Internal SCOT system error. Perform reset if needed
E1-66 Calibration condition error, wait for burner to restart
E1-67 Missing calibration – try resetting the boiler
E1-68 Ion base value is outside the factory limits or saved incorrectly – try resetting the boiler
E1-69 / E1-70 Parameter CRC fault – try resetting the boiler
E1-71 EK lockout failure – this is a permanent error
E1-72 SCOT flame amplifier – reset the boiler
E1-73 Printed circuit board (PCB) error – try resetting the boiler
H9-01 Outside sensor fault – try resetting the boiler
HC-01 Domestic hot water (DHW) temperature sensor error. The boiler will continue to operate but you need to Contact a heating engineer
HJ-08 High system pressure – the boiler needs to discharge water down to 0.8 bar
HJ-09 Low system pressure – increase the system pressure to 0.8 bar
HJ-10 Water pressure sensor fault
J6-01 Flow temperature sensor overheating due to a blocking fault or a lockout error – the valves of the radiator heating circuit may have an issue or the water pressure is low and needs filling
J6-20 Return temperature sensor overheating due to a blocking fault or a lockout error – try resetting the boiler
J6-21 Return temperature is higher than flow temperature. Burner operates itself after a small amount of time but if the problem repeats you need to Contact a heating engineer
JJ-64 Supply voltage is below low limit
U2-01 Supply voltage is above high limit, your boiler should continue to operate but you need to Contact a heating engineer
U4-65 OpenTherm room thermostat connection is defective – your boiler will continue to operation but the thermostat is out of operation
U4-66 CAN-bus timeout
U4-67 Remote reset supervision, switch off the power at the mains – if problem repeats Contact a heating engineer
UA-64 Blocking during boiler chip card (BBC) update
UA-65 Printed circuit board (PCB) requires a boiler chip card (BCC) update
UA-66 Boiler chip card ID (BCC-iD) of internal Electrically Erasable Programmable Read-Only Memory (EEPROM) is inconsistent
UA-67 Boiler chip card (BCC) is missing

Error Code HJ-08

If you are seeing the error code HJ-08 this could be due to a high system pressure. To resolve this issue you need to discharge the water down to 0.8 bar. As well as this, you should also bleed your radiators.