BoilerFaultCodesYour boiler has stopped working because its internal computer has detected a communication error with the burner control system.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: System fault burner control unit
What causes this fault?
This fault occurs when the boiler's main control centre loses its ability to 'talk' to the components that manage the gas burner. It is typically caused by a physical break in the internal wiring or a critical failure within the printed circuit board itself, preventing the boiler from firing safely. Essentially, the boiler has shut down because its internal systems can no longer coordinate the ignition process.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A boiler cover plan would cover faults like 604 — no call-out fees, no surprises.
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Could it be time for a new boiler?
If repair costs are adding up, a new energy-efficient boiler could be the smarter long-term choice.
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