High
lock-out on Worcester Bosch Greenstar 15sbi

Your boiler has failed to ignite after several attempts and has switched itself off for safety reasons, meaning it cannot currently provide heat 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.

What the manual says

Manufacturer manual

The burner will go out but, after a short pause, the appliance will make 5 attempts to restart sparking for 5 seconds and then 'lock-out'. This occurs if the gas service cock is turned off or if the boiler fails to light after a maximum of 5 attempts.

From this model's manual
Verified against the Worcester Bosch/Worcester Bosch Greenstar 15i System System installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

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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All 3 fault codes on the Greenstar 15sbi

Seeing a different code? Every code this model can display, in one place.

LOCKOUT LIGHT FLASHINGLOCKOUT LIGHT ON (CONSTANTLY)

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