BoilerFaultCodes.com
306 Emergency Lockout

Your boiler is still detecting a flame even though it has tried to shut off the gas supply, which is a safety conflict.

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now — this fault can be dangerous if ignored.

Technical description: Flame signal after closing the fuel supply

What causes this fault?

This fault occurs when the boiler's internal sensor detects a flame or an electrical current that looks like a flame even after the gas has been told to turn off. The most common reason is a gas valve that hasn't fully closed or an ignition electrode that is sending a false signal back to the main control board.

Typical repair cost £180-450 (including labour)

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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Protect yourself from future repair bills

A boiler cover plan would cover faults like 306 — no call-out fees, no surprises.

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