High Lockout
85 on Ideal Response

Your boiler is struggling to light or keep a flame burning correctly because the gas and air mixture isn't balanced.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

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

Technical description

Flame detection and mixture

What causes this fault?

This fault occurs when the boiler's internal sensor fails to detect a consistent flame after it tries to ignite. The root cause is usually a breakdown in the balance between gas and air, or a worn-out sensor that can no longer tell the control board that the fire is safely lit.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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