How much does it cost to fix boiler error code HW light On (flashing)?

Typical repair cost for the boiler HW light On (flashing) fault is £120-250 including labour.

HW light On (flashing) High

Boiler Fault Code HW light On (flashing)

Also written as HWLIGHTONFLASHING — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code HW light On (flashing) appears across 1 boiler brand and 1 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has sensed that the water inside it is getting too hot and has automatically switched itself off to prevent damage. (As reported on Worcester Bosch 24CDi BF)

Pick your boiler brand for the HW light On (flashing) fix

Worcester Bosch HW light On (flashing) 1 model

Source

Information for the HW light On (flashing) fault code is sourced from the official service / installation manual for each model that displays it. Read more about how we source fault codes →

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026