BoilerFaultCodesYour boiler has shut itself down for safety because it failed to light or detected a general system failure.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Default lockout
What causes this fault?
This fault occurs when the boiler's control system attempts to start the heating process but fails to detect a stable flame after several attempts. The most common reasons include a lack of gas supply to the unit, a worn-out ignition spark, or a component failure that prevents the burner from opening properly.
This fault is frequently seen during the first cold snap of winter when internal components like gas valves can stick after being inactive over the summer months.
DIY fix possible
Check that your gas pre-pay meter has credit (if applicable).Ensure your external gas emergency control valve is in the 'on' position.Press and hold the reset button for five seconds to see if the boiler restarts.
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A boiler cover plan would cover faults like 12 — 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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