Your boiler has tried to light several times but has been unable to detect a flame, causing the system to shut down for safety.
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
What causes this fault?
This fault occurs when the boiler's internal computer tries to start the burner multiple times but cannot confirm that a steady flame has been established. The most common reasons include a lack of gas supply to the unit, a blocked pipe that removes waste water, or dirty internal sensors that can no longer 'see' the flame effectively.
This fault is frequently seen during freezing winter temperatures, as the external condensate pipe can freeze solid, causing water to back up into the boiler and prevent it from lighting.
DIY fix possible
Check if your gas supply is active by testing other gas appliances like a hobEnsure your gas meter has credit if you use a pre-payment meterPress and hold the 'Reset' button for five seconds to see if the boiler restartsCheck that the condensate pipe (outside white plastic pipe) isn't frozen if the weather is very cold
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 12i System 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.