BoilerFaultCodesThe 6 most common faults
Your boiler has tried to light several times but cannot establish a flame, meaning your heating and hot water will not work.
Check that your gas emergency control valve is in the 'on' positionIf you have a prepayment meter, check that you have sufficient creditCheck if other gas appliances in your home, such as a hob, are workingReset the boiler by pressing the 'Reset' button
Your boiler has become too hot and has shut down as a safety precaution to prevent damage.
Check that the system water pressure is between 1 and 1.5 bar on the pressure gauge.Ensure all radiator valves and any isolation valves under the boiler are fully open.Bleed your radiators to remove any trapped air that might be blocking water flow.
Your boiler has shut down because it keeps losing water pressure, which usually indicates a leak somewhere in your heating system or a faulty internal component.
Check all visible radiators and pipework for signs of water leaksTop up the system pressure to 1.5 bar using the external filling loopReset the boiler to clear the fault code
Your boiler has started an ignition sequence but the flame keeps going out, meaning the system cannot stay lit long enough to heat your home.
Check the outside flue pipes for any obstructions like leaves, nests, or debris.Inspect the plastic condensate drain pipe for signs of freezing or blockages if the weather is very cold.If you use LPG, verify that your tank has enough fuel.
Your boiler has detected that the water pressure is too low to operate safely and has shut down as a precaution.
Locate the external filling loop, which is usually a silver flexible hose with two small valves.Slowly open both valves to allow water into the system while watching the pressure gauge.Close both valves tightly once the pressure gauge reaches 1.5 bar.
Your boiler has detected that there is too much water in the system, which can cause excessive strain on the pipes and safety valves.
Check that the filling loop valves are fully closed and not leaking water into the systemBleed a radiator from a bottom-floor valve to release excess water pressureMonitor the pressure gauge to ensure it returns to between 1.0 and 1.5 barRestart the boiler once the pressure has been lowered
on the Keston Heat 45
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