BoilerFaultCodesYour boiler has shut itself down for safety because it failed to light or detected an internal problem.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Boiler at lock-out
What causes this fault?
This fault occurs when the boiler has tried to ignite several times but failed to establish a stable flame. The most common reason is a lack of fuel reaching the burner, often due to a faulty gas valve or worn-out ignition sparks that can no longer light the gas safely.
DIY fix possible
Locate the reset button on the front control panel.Press and hold the reset button for several seconds.Check if your gas supply is active by testing another gas appliance like a hob.
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 9 (Flashing) — no call-out fees, no surprises.
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Potterton Envoy 30 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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