BoilerFaultCodesThe 6 most common faults
Your boiler has likely lost power or the electronic control board is failing to communicate with the display.
Check that the main boiler power switch or fused spur is turned onCheck your home's consumer unit (fuse box) to see if a circuit has trippedSwitch the power off for 30 seconds and then back on to attempt a reset
Your boiler has likely lost flame or suffered a lockout, meaning it has shut down for safety and cannot provide heating or hot water until reset.
Locate the reset button (usually indicated by a flame with a cross through it or the power button).Press and hold the reset button for five seconds.Ensure your gas supply is active and that your prepaid meter (if applicable) has credit.
Your boiler has failed to ignite and cannot produce heat or hot water, usually because the gas supply is blocked or the ignition spark is failing.
Check if your gas meter has credit and the isolation valve is openCheck if other gas appliances, like a hob, are working correctlyTry thawing the condensate pipe with warm water if it is frozen outsidePress the Reset button (indicated by a flame symbol with a cross)
Your boiler has detected low water pressure in the central heating system, which is preventing it from firing up.
Locate the filling loop (a flexible silver hose) underneath your boiler.Open the small taps on either end of the hose to let water into the boiler.Close the taps once the pressure gauge on the front of the boiler reaches between 1 and 1.5 bar.
Your boiler has detected an issue with the water pressure or the sensor that monitors it, preventing the system from heating up safely.
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 bar, use the filling loop underneath the boiler to increase it.Once the pressure is corrected, press the 'Reset' button to restart the boiler.
Your boiler has lost power or has a serious internal communication error, meaning it cannot operate or tell you what is wrong.
Check if your home's main electrical consumer unit has trippedEnsure the fused spur switch next to the boiler is turned onCheck if any other appliances on the same circuit are working
on the Glow-worm 38cxi
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