No light High

Worcester Bosch No light Fault Code

Also written as NOLIGHT — same fault.

The Worcester Bosch No light fault code means: your boiler appears to have no power and the display is completely dead, meaning it cannot provide any heating or hot water.. It appears on 5 Worcester Bosch models in our database.

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 power at control board. Possible solutions/checks: Permanent mains supply to boiler, Boiler mains switch ON, Fuse F1 - 2A Slow blow, Fuse F2 - 1.25A Anti-surge, Transformer (both coils below 100Ω. Otherwise replace control board.

What causes the Worcester Bosch No light fault?

This fault occurs when the electrical circuit inside the boiler is interrupted, preventing power from reaching the internal components. The most common reason is a blown internal fuse or a failure within the transformer, which acts as the heart of the boiler's electrical system. In some cases, a power surge or a short circuit on the main control board can cause the unit to shut down completely to prevent further damage.

Typical repair cost £120-350 (including labour)

DIY fix possible

Check if the main electricity switch for the boiler is turned onCheck your home's consumer unit (fuse box) to see if a circuit breaker has trippedReplace the fuse in the external boiler spur switch with a new 3-amp fuse

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Worcester Bosch models that show the No light fault code

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

Source

Worcester Bosch No light 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