BoilerFaultCodesYour boiler has shut itself down as a safety precaution because it has detected an internal fault or overheating.
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 sensors detect that the system is getting too hot or that water isn't moving through the unit correctly. It is often triggered by a circulation issue, such as a failing pump or a blockage, which causes the heat exchanger to reach a dangerous temperature. To prevent any damage, the boiler automatically shuts down and locks itself for your safety.
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 E12 — 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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