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 safety sensors detect that the temperature has exceeded safe operating limits, triggering an immediate shutdown to protect the system. The most common reason is a restriction in water flow or a failure in the components that monitor heat, such as a faulty limit thermostat or a malfunctioning control board.
This issue is more frequent during the first cold snap of autumn when a heating system is turned on for the first time after months of inactivity, often revealing pump stickiness or airlocks.
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.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like E30 — 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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