BoilerFaultCodesYour boiler has stopped working completely and entered a safety lockout mode to prevent further issues.
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 or detect a stable flame. The most common reasons are a lack of gas reaching the burner, a worn-out ignition spark, or the internal control board failing to recognize that the boiler has successfully lit.
This fault is slightly more common in winter when increased demand on the gas network or freezing temperatures can affect gas pressure and component reliability.
DIY fix possible
Locate the reset button on the control panelPress and hold the reset button for several secondsWait for the boiler to attempt to restartCheck that your gas pre-payment meter (if applicable) has credit
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 F (Flashing) — no call-out fees, no surprises.
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Potterton Envoy System 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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