BoilerFaultCodesYour boiler has detected a specific internal electronic fault with the valve that controls the gas supply, meaning the appliance cannot ignite safely and will remain shut down.
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 – Propane Dungs BM771 SL 040
What causes this fault?
This fault occurs when the boiler's main control board loses communication with or detects an electrical failure within the gas valve assembly. The most common reason is an internal component failure inside the valve itself, which prevents it from opening to allow fuel into the burner 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.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like E80-451 — no call-out fees, no surprises.
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Worcester Bosch 24/28CDi II RSF 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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