BoilerFaultCodes.com
FA High Lockout

Your boiler is still detecting a flame even though the gas should have been turned off, which is a safety conflict preventing the system from running.

Call an engineer soon

Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Flame detected after gas shut off.

What causes this fault?

This fault occurs when the boiler's internal sensors continue to detect a flame even after the system has commanded the gas to stop flowing. The most common reasons are a gas valve that is physically stuck open or failing to seal correctly, or a faulty sensor providing a false signal to the control board.

Typical repair cost £120-£350 (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

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