High Lockout
Fast flash on Worcester Bosch Greenstar Ri

Your boiler has detected a critical internal error with its fan or electronic memory and has shut down for safety.

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

Volatile lockout sensor fan or code plug

What causes this fault?

This fault occurs when the boiler's main computer loses communication with the fan or the small electronic chip that stores the appliance's settings. The most common reason is an electrical failure within the fan motor or a loose connection on the internal circuit board that prevents the boiler from safely managing the airflow. Without this constant data exchange, the system shuts down immediately to prevent an unsafe build-up of gas.

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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Related fault codes

C6View →E9View →

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