BoilerFaultCodesThe 6 most common faults
Your boiler has tried to light several times but cannot start a flame, which means your heating and hot water will not work.
Check if other gas appliances in your home, like a hob, are working to confirm gas supply.Ensure your gas meter has credit if you use a prepay meter.Restart the boiler by pressing the reset button for five seconds.
Your boiler has shut down because it has reached an unsafe temperature and needs to be cooled down and reset.
Ensure all radiator valves and boiler bypass valves are openCheck that the system water pressure is at the correct level (usually 1.0 to 1.5 bar)Once the unit has cooled, press the reset button on the control panel
Your boiler has stopped working because the water pressure is too low for it to run safely.
Locate the external filling loop, which is usually a silver flexible hose with two small valves.Slowly open both valves one at a time until you hear water flowing into the system.Watch the pressure gauge and close both valves tightly once it reaches between 1.0 and 1.5 bar.
Your boiler has lost its connection to the thermostat or external controller, meaning the two devices can no longer talk to each other to manage your heating.
Check if the batteries in your wall thermostat need replacing.Ensure the thermostat is within signal range of the boiler.Turn the boiler power off and on again at the fused spur to restart the communication sequence.
Your boiler has detected that the water coming back from your radiators is dangerously hot and has shut down to protect itself.
Check that all radiator valves are fully openEnsure there is no air trapped in the system by bleeding your radiatorsCheck that the internal pump is running if you are able to hear it
Your boiler has detected that water is heating up too quickly because it isn't moving through the system fast enough.
Ensure all radiator valves are fully openCheck that the central heating pump is runningCheck the system pressure and top up if it is below 1 bar
on the Johnson Starley Warmcair DW
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 Johnson Starley 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