BoilerFaultCodesThe 6 most common faults
Your boiler has encountered a general issue and has stopped working as a safety precaution.
Locate the On/Off switch on the boiler control panel.Turn the switch to the (0) position to power down the unit completely.Wait for at least five seconds.Turn the switch back to the (I) position to restart the boiler.
Your boiler has lost the pressure it needs to circulate water, so it has turned off to prevent damage.
Locate the external filling loop or internal filling key under your boiler.Slowly open the valves to let water into the system until the pressure gauge reads between 1 and 1.5 bar.Close the valves tightly and turn your heating on to see if the fault clears.
Your boiler pressure is too high, which puts unnecessary stress on the internal system components.
Locate a radiator in your home that has a bleed valve.Place a small container and cloth underneath the valve to catch water.Use a radiator key to slowly open the valve until water begins to trickle out, watching the boiler's pressure gauge until it drops back to 1.5 bar.
Your boiler is failing to start because it cannot clear stale air from the system, which is keeping the internal fan from turning on.
Full guide for 02Your boiler is struggling to communicate with the display panel or controller, meaning it cannot receive instructions to heat your home or water.
Full guide for 12Your boiler's central control computer has encountered an internal error and stopped working, meaning the unit will not start until it is repaired.
Full guide for 13on the Glow-worm 23c
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 Glow-worm 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