BoilerFaultCodesYour boiler has shut down to protect itself because a safety sensor has detected a fault with the burner or the ignition process.
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 control system fails to detect a steady flame after several attempts to light. The most common reasons are a buildup of carbon on the ignition parts, an inconsistent fuel supply, or a sensor that has become too dirty to 'see' the flame. It functions as a safety shutdown to ensure gas does not flow without being safely burned.
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 E04 — 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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