High Lockout
1074 W on Worcester Bosch Greenstar 8000 Life/Style

Your boiler has lost communication with its internal thermometer, meaning it cannot safely monitor the temperature of the water circulating through your radiators.

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

No signal from the flow temperature sensor available – connect the plug to the flow temperature sensor correctly or temperature sensor could need replacing

What causes this fault?

This fault occurs when the boiler's main control board loses the electronic 'handshake' with the sensor that monitors outgoing water temperature. The most common reason is a loose or corroded wiring connection, but it can also happen if the internal sensor has developed a physical defect and can no longer send a steady signal.

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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