BoilerFaultCodesYour boiler has stopped working and locked itself for safety, likely because it failed to light or detected an internal issue.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: FLASHING. Boiler at lock-out
What causes this fault?
This fault occurs when the boiler tries to light but fails to detect a stable flame after several attempts. The most common reasons are a worn-out ignition spark, a dirty sensor that can't 'see' the flame, or a technical failure within the gas valve or control board.
This issue often surfaces during the first cold snap of autumn when the boiler is worked harder after being mostly idle during the summer months.
DIY fix possible
Locate the reset button on the control panelPress and hold the reset button for several secondsWait to see if the boiler restarts and the flashing number 9 disappears
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 — no call-out fees, no surprises.
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Potterton Envoy 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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