BoilerFaultCodesYour boiler is struggling to light because it cannot detect a steady flame after starting up.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: ignition
What causes this fault?
This fault occurs when the boiler successfully creates a spark and ignites the gas, but the flame goes out almost immediately or isn't recognized by the system. The most common reasons are a worn-out sensing probe that can no longer 'see' the flame, or a gas valve that isn't delivering enough fuel to maintain a steady burn.
DIY fix possible
Check that your gas supply is turned on at the meterCheck if other gas appliances, like a hob, are working correctlyIf it is freezing outside, check if your white plastic condensate pipe is frozen and thaw it with warm waterPress the Reset button (indicated by a flame symbol with a cross through it)
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like S.23 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Glow-worm Flexicom cx is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
Affiliate links — we may earn a commission at no extra cost to you.