BoilerFaultCodesThe 6 most common faults
Your boiler has tried to light itself several times but cannot establish a flame, meaning you have no heating or hot water.
Check that your gas emergency control valve is in the 'on' positionIf you have a prepayment meter, check that you have credit availableCheck if other gas appliances, like a hob, are working to confirm gas flowPress the Reset button once to see if the boiler restarts
Your boiler has reached an unsafe temperature and has shut itself down to prevent damage.
Check that all radiator valves and boiler isolation valves are fully openEnsure the system pressure is between 1.0 and 1.5 bar on the pressure gaugeBleed all radiators to remove trapped air that might be blocking water flow
Your boiler has shut down because it keeps losing water pressure and has had to be reset too many times in a single day.
Check all visible radiators, valves, and pipework for any signs of water leaksRepressurise the system to 1.5 bar using the external filling loopReset the boiler to clear the fault code
Your boiler is struggling to keep a flame lit, often because the pipes that carry air in or waste water out are blocked or frozen.
Check the external plastic flue pipes for any obstructions like leaves or debrisIf the weather is freezing, pour warm (not boiling) water over the external condensate drainage pipeReset the boiler by pressing the 'Reset' button
Your boiler has detected that the water pressure is too low to operate safely and has shut down to protect itself.
Locate the external filling loop, which is usually a silver flexible hose with one or two small taps.Slowly open the taps until you hear water entering the system.Watch the pressure gauge and close the taps firmly once the needle reaches between 1.0 and 1.5 bar.
Your boiler has been manually reset too many times in a short period and has temporarily locked itself out as a safety precaution.
Turn the boiler power off at the fused spur switchWait for at least 15 to 20 minutes for the internal timer to clearTurn the power back on and see if the boiler restarts without immediate manual resetting
on the Keston Heat 80
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