BoilerFaultCodesThe 6 most common faults
Your boiler has lost the correct water pressure needed to circulate heat around your home.
Locate the filling loop (usually a silver braided hose with one or two valves) underneath the boiler.Open the valve(s) to allow cold mains water into the system until the pressure gauge reads between 1.0 and 1.5 bar.Close the valve(s) firmly and check the display to see if the fault has cleared.
Your boiler has detected that the water pressure inside your heating system has dropped too low to operate safely.
Locate the filling loop (a flexible silver hose) underneath the boiler.Open the valves at both ends of the hose to allow water into the system.Monitor the pressure gauge on the boiler front until it reaches 1.5 bar, then securely close both valves.
Your boiler has detected an error and needs a manual restart to clear the internal safety lockout.
Locate the reset button or dial on the front of your boiler control panel.Press and hold the reset button for 3 to 5 seconds.If the boiler does not restart, turn the power off at the fused spur or mains switch for 60 seconds, then turn it back on.
Your boiler has stopped working because the amount of water inside your heating system has dropped below the necessary level to operate safely.
Locate the external filling loop, which is usually a silver braided hose with one or two valves located underneath your boiler.Gradually open the valve(s) to allow mains water into the system until the pressure gauge on the front of the boiler reads between 1.0 and 1.5 bar.Close the valve(s) tightly and check for any leaks around the connection points.
Your boiler has taken in too much water, causing internal pressure to rise above safe operational limits.
Locate a radiator in your home with a bleed valve.Place a cloth or small container under the valve.Open the valve slowly using a radiator key until water starts to trickle out and the pressure gauge on the boiler drops to between 1.0 and 1.5 bar.Close the valve securely.
Your boiler has lost all power, meaning it cannot currently provide any heating or hot water to your home.
Check that your boiler's power switch is turned on.Look at your home's fuse box or consumer unit to see if a trip switch or circuit breaker has flipped.Ensure the plug socket supplying the boiler is working by testing it with another appliance.
on the Johnson Starley Quantec C
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