High
Lock state cause on Biasi Gaia

Your boiler has switched itself off because it has reached an unsafe temperature, likely due to a blockage or a failure in how the water is moving through the system.

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

Intervention of the safety thermostat (primary hydraulic circuit)

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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