BoilerFaultCodesYour boiler has detected a failure with the internal gas control valve, meaning it cannot safely ignite to provide heating or hot water.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: Gas Valve – Natural Gas Dungs BM771 SL 040
What causes this fault?
This fault occurs when the boiler's main control board loses electrical communication with the gas valve or detects that the valve is physically unable to open. The most common reason is an internal mechanical failure within the valve itself or a loose connection in the wiring harness that prevents the flow of gas required for ignition.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
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A boiler cover plan would cover faults like E80-450 — no call-out fees, no surprises.
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