BoilerFaultCodes.com

Keston S30 Fault Codes

System Natural Gas 30 kW 2013-present
GC Number: 41-311-73

The fault code is already on your display

Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →

Most common fault codes

C0
Your boiler's internal memory chip is not communicating correctly with the main control board, preventing the system from starting up.
Gas Safe engineer required · £120-£350
C2
Your boiler’s internal computer chip has encountered a communication error or is missing, preventing the system from running safely.
Gas Safe engineer required · £180-350
F0
Your boiler's main control computer is missing a vital activation chip, which means the system cannot start up or provide any heat.
Gas Safe engineer required · £120-250

All 19 fault codes

Code Severity Plain English
0 Low Your boiler is working perfectly fine and is simply resting until you turn on your heating or hot water.
C Low Your boiler is working correctly and has simply reached the maximum temperature you set, so it is pausing temporarily until the water cools down enough to fire up again.
C And Burner Light Low Your boiler is working normally and currently heating your radiators or hot water.
C0 High Your boiler's internal memory chip is not communicating correctly with the main control board, preventing the system from starting up.
C2 High Your boiler’s internal computer chip has encountered a communication error or is missing, preventing the system from running safely.
F And Burner Light Low Your boiler has detected very cold temperatures and has automatically turned itself on to prevent the internal pipes from freezing.
F0 High Your boiler's main control computer is missing a vital activation chip, which means the system cannot start up or provide any heat.
F1 High Your boiler has detected that the water pressure in the system is too low, causing it to stop running for safety.
F2 High Your boiler has lost its flame signal during operation, meaning and it can no longer safely heat your water or radiators.
F3 High Your boiler has detected an issue with its fan, meaning it cannot safely circulate air or clear exhaust fumes and has shut down as a safety precaution.
F4 High Your boiler has detected that a temperature sensor is not communicating correctly, meaning the system cannot tell how hot the water is and has stopped working for safety.
F5 High Your boiler has stopped working because it cannot properly measure the temperature of the water coming back from your radiators.
F6 Low Your boiler has lost communication with the sensor that measures the temperature outside, which helps it run more efficiently.
F7 High Your boiler has detected that the electricity supply coming into your home is at a lower voltage than it needs to operate safely.
F9 High Your boiler's internal computer has encountered a critical error and cannot communicate with the rest of the system.
L1 High Your boiler has shut down because the water inside it has become too hot, likely due to a circulation problem.
L2 High Your boiler has lit correctly but the flame has gone out unexpectedly, often due to a fuel supply issue or a blockage in the condensate pipe.
L5 High Your boiler has been manually reset too many times in a short period and has locked itself out to prevent further damage or safety issues.
L6 High Your boiler thinks it sees a flame even though it isn't currently trying to light, causing the system to shut down for safety.

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