BoilerFaultCodesYour boiler is failing to light the gas, meaning it has shut down to prevent unburnt gas from building up.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Flame not detected after 4 ignition attempts
What causes this fault?
This fault occurs when the boiler's internal computer doesn't see a flame after several attempts to light the gas. The most common reasons include a lack of gas reaching the unit, worn-out spark electrodes that can no longer create a flame, or a dirty sensor that fails to 'see' the heat even when it is present.
This fault is frequently seen during extreme cold snaps, as the external condensate pipe can freeze and back up, preventing the boiler from completing the ignition process.
DIY fix possible
Check if you have credit on your gas meter or if other gas appliances are workingIf it is freezing outside, check if the white plastic condensate pipe is frozen and thaw it with warm waterPress the Reset button for five seconds until the display clears
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 EA — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Worcester Bosch Greenstar 25Si 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.