BoilerFaultCodesThe 6 most common faults
Your boiler has tried to start up but cannot light the gas flame required to provide heating and hot water.
Check that your gas emergency control valve is in the 'on' positionIf you have a prepay meter, check that you have sufficient creditTest other gas appliances, like a hob, to see if the gas supply is activePress the Reset button on the boiler control panel
Your boiler has switched itself off because the water inside it has become too hot, usually caused by a blockage or a pump failure.
Check that all radiator valves are fully open to allow water to flow.Inspect the system pressure gauge and top it up to 1.5 bar if it is too low.Wait for the boiler to cool down and press the 'Reset' button.
Your boiler has stopped working because the water pressure is too low and needs to be topped up.
Locate the filling loop (usually a silver flexible hose) underneath the boiler.Slowly open the valve or valves on the hose until you hear water moving.Monitor the pressure gauge until it reaches between 1.0 and 1.5 bar, then close the valves tightly.Restart the boiler to clear the fault code.
Your boiler has stopped working because water is not flowing through the system correctly, which is causing it to overheat.
Check that the boiler pressure is between 1.0 and 1.5 bar on the gauge.Ensure all radiator valves and isolation valves under the boiler are fully open.Gently bleed air from your radiators using a radiator key.
Your boiler has detected that the water pressure inside the system is either too low or too high to operate safely.
Check the pressure gauge on the front of the boiler; it should be between 1 and 1.5 bar.If the pressure is below 0.5 bar, use the filling loop valves underneath the boiler to top it up until it reaches 1.2 bar.If the pressure is above 2.5 bar, bleed a radiator using a radiator key to release water and lower the pressure.Reset the boiler once the correct pressure is achieved.
Your boiler has stopped working because it cannot light the flame or the internal drainage pipe is backed up with water.
Check if your gas supply is active (e.g. check other gas appliances or prepay meter credit).Inspect the white plastic pipe exiting the building for ice or blockages; gently thaw with warm water if frozen.Press and hold the reset button for 5 seconds to try and restart the system.
on the Heatline Sargon 24
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 Heatline 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