Keston Combi Boiler Error Codes
Keston Combi Boiler Error Codes

Keston Combi Boiler Error Codes

Keston Combi Boiler Error Codes Listed below are the common Keston fault codes as described by the boiler manufacturer along with a possible cause. Keston combi boiler error codes are an important part of your boiler maintenance. If you don’t check your Keston C36 combi boiler error codes, you may end up with problems down the line. Error codes will help to prevent costly breakdowns and unexpected bills. In this table we’ll teach you how to manually read your fault code and give you some top tips on what to do if you have any problems identifying the code.

Keston Boiler Error Code Solutions

Fault CodePossible Cause
E01Ignition failure – the boiler has attempted to light 5 times and not succeeded – check the gas supply is on
E02False flame – possibly a problem with the power supply
E03Boiler overheat – check that any valves to the heating circuit have not been shut down, no air in the system and that the water pressure is correct
E05Fan failure – boiler cannot detect fan rotation – check fan operation and both connectors onto fan
E07Flue overheat – check combustion and flue temperature vs. return temperature – the flue temperature should be no more than 10C above return temperature. Possible heat exchanger fault.
E08Flame circuit error – possible control box fault
E09Valve drive error – possible gas valve or control box fault
E10Control box errors – possible faulty control box
E11The automatic test for calibration of flow and return sensors has failed check both flow and return sensors are located on the correct pipes and are producing the correct readings
E12 E22Control box errors – possible faulty control box
E23Water filling error – check water pressure sensor
E24Water pressure lost 4 times in 24 hours – possible leak, check system and boiler
E25Control box errors – possible faulty control box
E26Flame drop out – check for obstruction of the flue and/or air terminals, blockage/freezing of the drain pipe or a low gas supply (LPG).
E30Flow sensor short circuit – check connections to flow sensor
E31Flow sensor open circuit – check connections to flow sensor are in place
E32DHW sensor short circuit – check connections to domestic hot water (DHW) sensor
E33Domestic hot water (DHW) sensor short circuit – check connections to DHW sensor are in place
E34Mains supply voltage < 180V – may be a problem with your power supply
E35Mains supply frequency incorrect – may be a problem with the power supply
E37Water pressure error – increase the system water pressure
E38Reset key fault – replace fascia PCB
E40Water pressure too high
E41Communication error between fascia and control box – check cables
E43Return sensor short circuit – check connections to return sensor
E44Return sensor open circuit – check connections to return sensor are in place
E45Flue sensor short circuit – check connections to flue sensor
E46Communication error between fascia and control box – check cables
E99Flue sensor short circuit – check connections to flue sensor are in place

S30 System Gas Boiler Error Codes

Fault CodePossible Cause
0The boiler is in standby mode awaiting either a central heating call or hot water demand
CThe boiler has a call for central heating / hot water but the appliance has reached the desired temperature set on the boiler
C and Burner LightThe boiler is operating for central heating / hot water
F and Burner LightThe boiler is operating in frost mode
F0Boiler Chip Card (BCC) not fitted
F6Outside sensor failure
F7Low mains voltage
F9Printed circuit board (PCB) Fault
L55 boiler resets in 15 minutes
L6False flame lockout
C0Boiler Chip Card (BCC) activation fault
C2Boiler Chip Card (BCC) fault
F1Low water pressure
L1Flow temperature overheat
F2Flame loss
L2Flame loss
F3Fan fault
F4Control / No flow thermistor
F5Return thermistor

C40 C55 Combi Gas Boiler

Fault CodePossible Cause
EnnFault causing a boiler shutdown
E00Flame detected when not expected – check boiler earth and probe condition
E02No ignition after restart – check gas supply, gas valve operation and ignitor electrode spark generation
E03Gas valve faulty or not connected
E04Power has been reset whilst boiler was in lockout
E11Internal electronics error – rest or replace control box
E18Flow overheat – check water circulation
E19Maximum return temperature exceeded – check circulation
E25Flow temperature increased too quickly – check water circulation
E30Difference between flow and return temperatures too high – check circulation.
E31Flow thermistor short circuit – check/replace connections/thermistor
E32Return thermistor short circuit – check/replace connections/thermistor
E36Flow thermistor open circuit – check/replace connections/thermistor
E37Return thermistor open circuit – check/replace connections/thermistor
E44Low water pressure

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