Blue light on Low

Worcester Bosch Blue light on Fault Code

Also written as BLUELIGHTON — same fault.

The Worcester Bosch Blue light on fault code means: your boiler is working perfectly, and the blue light simply indicates that it is currently powered on and ready to provide heating or hot water.. It appears on 4 Worcester Bosch models in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Boiler is operational and firing.

DIY fix possible

No action is required as the boiler is operating normally.

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Worcester Bosch models that show the Blue light on fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Worcester Bosch Blue light on 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 7 July 2026