BoilerFaultCodesThe 6 most common faults
Your boiler is not firing up to provide heat or hot water because it is having trouble starting the flame.
Check that your gas meter is topped up with creditEnsure the gas stopcock (yellow handle) is turned to the 'on' positionCheck if other gas appliances, such as a hob, are working correctlyPress the Reset button on the boiler control panel
Your boiler has become too hot and has shut itself down as a safety precaution to prevent damage.
Check that the boiler pressure gauge is between 1.0 and 1.5 bar and top up if necessary.Ensure all radiator valves and any isolation valves under the boiler are fully open.Gently bleed your radiators to remove any trapped air from the system.
Your boiler has shut down because it keeps losing water pressure and needs a manual top-up or a leak fixed.
Check all radiators and pipework for visible signs of a water leakLocate the external filling loop and top up the pressure to between 1.0 and 1.5 barReset the boiler to clear the fault code
Your boiler is struggling to keep its flame alight because it cannot breathe properly or get enough fuel.
Check the outdoor white plastic flue pipes for any obstructions like leaves or bird nestsCheck the outdoor condensate drain pipe for signs of freezing or blockagesIf you use LPG, verify that your gas tank has not run out
Your boiler has stopped working because the water pressure inside the system has dropped too low.
Locate the filling loop (the flexible silver hose) underneath or near the boilerSlowly open the one or two taps/valves on the filling loop to let water into the systemWatch the pressure gauge and close the taps once the needle reaches between 1.0 and 1.5 barReset the boiler to clear the error code
Your boiler has stopped working because it has been reset too many times in a short period and has locked itself out for safety.
Turn the power to the boiler off at the fused spur switchWait for 30 secondsTurn the power back on to clear the lockout memory
on the Keston System S40
Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.
Call a Gas Safe engineer if…
- You can smell gas or see signs of a leak
- The Keston shows an Emergency or High severity code
- The boiler keeps locking out after repeated resets
- You've tried the DIY checks and the fault hasn't cleared
- There's visible water leaking from the boiler
- The flame is yellow or orange instead of blue