BoilerFaultCodesYour boiler has shut itself down as a safety precaution because it has detected an internal fault that could lead to overheating or unsafe operation.
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 temperature exceeds safe limits, triggering a safety shutdown to prevent damage. The most common reasons are a failure in the pump preventing water from moving through the system, or a faulty sensor incorrectly reporting an overheat. It can also be caused by a blockage in the heat exchanger or air trapped within the unit.
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.
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A boiler cover plan would cover faults like E23 — 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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