BoilerFaultCodesYour boiler has lost its flame during operation, meaning it can no longer heat your water or home safely.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: All Boilers
What causes this fault?
This fault occurs when the boiler's internal sensors detect that the flame has unexpectedly gone out while the unit was trying to provide heat. The most common reasons include a lack of gas reaching the burner, dirty internal components that can no longer sense the heat, or a mechanical failure within the ignition system. Because the boiler cannot maintain a consistent fire, it shuts down as a safety precaution.
This fault is more common during extreme cold snaps, as freezing temperatures can cause the external gas regulator or condensate pipe to block, leading to flame failure.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like 504 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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