HW light On (flashing) High

Worcester Bosch HW light On (flashing) Fault Code

Also written as HWLIGHTONFLASHING — same fault.

The Worcester Bosch HW light On (flashing) fault code means: your boiler has sensed that the water inside it is getting too hot and has automatically switched itself off to prevent damage.. It appears on 1 Worcester Bosch model 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: Over temperature shut-down if water temperature 8°C above set value. Ten second wait.
Typical repair cost £120-250 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Worcester Bosch models that show the HW light On (flashing) fault code

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

Source

Worcester Bosch HW light On (flashing) 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