BoilerFaultCodesYour boiler has failed to light several times and has locked itself for safety, meaning you have no heating or hot water at the moment.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Ignition lockout
What causes this fault?
This fault occurs when the boiler attempts to light the burner but fails to detect a stable flame after several tries. The most common reasons include a worn-out ignition electrode that can't create a spark, or an issue with the gas supply preventing fuel from reaching the burner.
This fault is more frequent during the first cold snap of winter, as internal parts may seize after being idle or gas valves can struggle with the sudden increase in demand.
DIY fix possible
Check if your home gas supply is active (e.g. check other gas appliances or your meter credit)If it is freezing outside, check if your white plastic condensate pipe is frozen and thaw with warm water if neededPress and hold the 'Reset' button for 5 seconds until the light stops flashing
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 Slow flash (normally off, flashes on), Lockout reset: Flashing (reset required) — no call-out fees, no surprises.
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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.
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