BoilerFaultCodesThe 6 most common faults
Your boiler is unable to light the flame needed to heat your water and home, often because the gas supply is interrupted or there is a problem with the internal spark.
Check that your gas emergency control valve is in the 'on' positionIf you have a pre-payment meter, verify that you have enough creditReset the boiler by turning the selector knob to 'Reset' for 5 seconds and then back to the heating/hot water position
Your boiler has switched itself off because the water inside has become too hot, usually caused by a blockage or a pump that isn't circulating water correctly.
Check that all radiator valves are fully open to ensure water can flow.Ensure the boiler pressure is between 1 and 1.5 bar on the pressure gauge.Once the boiler has cooled down, attempt to reset it by turning the dial to 'Reset' for a few seconds.
Your boiler has stopped working because the water pressure is too low, usually because the system needs top-up or there is a small leak.
Locate the filling loop (usually a silver flexible hose) underneath the boiler.Slowly open the valve or valves on the filling loop until you hear water entering the system.Watch the pressure gauge until it reaches between 1.0 and 1.5 bar, then close the valves tightly.
Your boiler has stopped working because water is not moving through the system properly, which is causing the unit to get too hot too quickly.
Check that your boiler pressure is between 1.0 and 1.5 bar on the gauge.Ensure all radiator valves are fully open to allow water to flow.Check if any radiators need bleeding to remove trapped air.
Your boiler has stopped working because the water pressure inside the system is either too empty or has become overfilled.
Check the pressure gauge on the front of the boiler; it should be between 1.0 and 1.5 bar.If the pressure is below 1.0, use the filling loop valves underneath the boiler to carefully add water until the needle reaches 1.2 bar.If the pressure is above 2.5, you may need to bleed a radiator to release excess water and bring the pressure down.
Your boiler has shut down because it has reached an unsafe temperature and needs to cool down and be reset.
Switch off the electricity supply to the boiler and wait 15 minutes for it to cool down.Check that your radiator valves are open and that the system pressure is between 1 and 1.5 bar.Turn the boiler back on and press the 'Reset' button.
on the Heatline Sargon 28
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