BoilerFaultCodesYour boiler has failed to ignite, meaning it cannot create the flame needed to provide you with heating or hot water.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Burner failed to light. Check gas supply and gas valve operation. Check fan and spark operation. Check flue for blockage. Clean or replace ionisation probe & lead. Check condensate outlet not blocked & vent tube is clear
What causes this fault?
This fault occurs when the boiler's control system attempts to start the burner but fails to detect a stable flame after several attempts. The most common reasons include a lack of gas reaching the unit, a dirty or worn-out sensor that can't 'see' the flame, or a build-up of debris in the internal components that prevents a successful spark.
This fault is frequently seen during the first cold snap of winter when a blocked condensate pipe can freeze, causing water to back up and prevent the boiler from lighting.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
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A boiler cover plan would cover faults like A01 — no call-out fees, no surprises.
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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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