BoilerFaultCodesYour boiler has shut down completely because an internal safety sensor has detected a critical fault that requires a professional inspection.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: The safety devices have been activated (lockout)
What causes this fault?
This fault occurs when the boiler's internal safety circuit is broken, triggering an immediate shutdown to protect the appliance from damage. The most common reason is a failure in the main control board or a triggered overheat sensor that prevents the system from operating safely. It can also be caused by loose internal wiring or a communication error between the boiler's electronic components.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
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A boiler cover plan would cover faults like E09 — 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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