BoilerFaultCodesYour boiler has detected an internal communication error between its main control boards, meaning it cannot operate safely and has 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: BMM fault.
What causes this fault?
This fault occurs when the two internal computers inside your boiler stop talking to each other. It is usually caused by a physical failure of the electronic circuits or a loose connection in the internal wiring, meaning the boiler can no longer verify it is operating safely. Because the system can't confirm vital safety checks, it shuts down completely as a protective measure.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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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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