BoilerFaultCodesThe 6 most common faults
Your boiler has failed to light the flame needed to provide heating or hot water, and it has now locked itself out for safety.
Why it happens: This fault occurs when the temperature sensor inside your hot water storage tank detects that the water has dropped to a near-freezing level. To protect the internal components from being damaged by expanding ice, the boiler temporarily pauses operation until the water temperature rises to a safe level. This is typically caused by extremely cold incoming mains water or a storage tank located in an unheated area like a garage or loft.
Full guide for F1Your boiler is not receiving enough gas or cannot create a flame to start the heating process.
Check if your gas prepay meter has creditEnsure your main gas stopcock is turned to the 'on' positionCheck if other gas appliances, like a hob, are working correctlyPress the reset button (flame symbol with a cross) for five seconds
Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
Locate the filling loop, which is a silver braided hose with one or two valves located underneath your boiler.Gradually open the valve(s) to let 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 to ensure no water continues to leak into the system.
Your boiler is struggling to pump water around your heating system correctly, which is likely due to low system pressure or a blockage.
Check your boiler's pressure gauge and ensure it is between 1 and 1.5 bar.If the pressure is below 1 bar, use the filling loop underneath the boiler to top it up to the recommended level.Restart your boiler and check if the fault clears.
Your boiler was working but the flame has unexpectedly gone out, causing the system to stop for safety.
Check if other gas appliances in your home, like a hob, are working to confirm gas supply.If it is freezing outside, check if the white plastic condensate pipe leading outdoors is frozen and thaw it with warm water.Press the reset button (flame symbol with a cross) for five seconds to restart the boiler.
Your boiler has detected that there is not enough water circulating inside the system to carry the heat away, so it has shut down to prevent damage.
Locate the external filling loop, which is usually a silver braided hose with one or two valves located underneath the boiler.Open the valve(s) to allow mains water to enter 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 once the correct pressure is reached.
on the Glow-worm Ultracom 2 SXI
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
Avoid the next call-out bill
Monthly cover means no unexpected bills when your boiler breaks down.
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