BoilerFaultCodesThe 6 most common faults
Your boiler has detected a general internal malfunction and has shut down as a safety precaution, meaning you currently have no heating or hot water.
Locate the reset button on the main control panelPress and hold the reset button for approximately 5 secondsWait 2 minutes for the system to attempt a restart
Your boiler has tried to start several times but failed to light, causing the system to lock itself out for safety.
Check that your gas prepayment meter has creditEnsure the gas stopcock valve is fully openPress the reset button on the control panel once
Your boiler's internal computer has encountered a memory error and can no longer process data correctly.
Switch the boiler off at the main electrical fused spur switchWait for 60 secondsSwitch the power back on and see if the display clears
Your boiler has stopped working because the water level inside the heating system has dropped too low.
Locate the filling loop (usually a silver flexible hose) underneath or near the boiler.Slowly open the valve or valves on the loop until you hear water flowing.Watch the pressure gauge and close the valves once it reaches between 1 and 1.5 bar.
Your boiler has stopped working because it cannot detect any water pressure, which means it has shut down to protect itself from damage.
Check the pressure gauge on the front of the boiler or underneathIf the pressure is below 1 bar, use the external filling loop to top up the system to 1.5 barReset the boiler using the control panel to see if the code clears
Your boiler has failed to light after several attempts and has locked itself out for safety.
Check that your gas supply is turned on and other gas appliances are working.Ensure you have credit on your gas meter if you use a prepay system.Press and hold the reset button for five seconds to restart the ignition sequence.
on the Johnson Starley Comet 100
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