BoilerFaultCodesWorcester Bosch Blue light: Off / Lockout: Off Fault Code
Also written as BLUELIGHTOFFLOCKOUTOFF — same fault.
The Worcester Bosch Blue light: Off / Lockout: Off fault code means: your boiler has completely lost all electrical power, meaning it cannot operate your heating or hot water at all.. It appears on 2 Worcester Bosch models in our database.
Technical description: No power at control board
DIY fix possible
Check your home's fuse box or consumer unit to see if the RCD or boiler circuit breaker has tripped.Verify the fused spur switch located near the boiler is turned on.Ensure the plug or connection at the fused spur is secure and the fuse inside the spur hasn't blown.
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Gas Safe Register →Worcester Bosch models that show the Blue light: Off / Lockout: Off fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch Blue light: Off / Lockout: Off fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026