High
Red LED illuminated on Halstead Finest Gold

Your boiler has detected a safety fault and has locked itself to prevent operation, meaning you currently have no heating or hot water.

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

Safety Lockout. There is a fault condition preventing operation of the appliance (e.g., air pressure switch, water flow switch, or overheat thermostat fault during power up).

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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