BoilerFaultCodesYour boiler has shut down because a safety sensor has detected a problem with how the flue gases are being cleared or handled.
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 safety monitoring system detects that harmful exhaust gases are not being safely pushed out of the flue or that the air supply is restricted. The most common reasons are a malfunctioning fan that cannot clear the gases, a blocked venturi tube, or a sensor that is failing to confirm the boiler is breathing correctly.
This fault is more common during periods of high wind, which can cause pressure fluctuations in the flue that trigger the safety sensors.
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 E03 — 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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