How much does it cost to fix boiler error code HW light on PCB 40 flashing?

Typical repair cost for the boiler HW light on PCB 40 flashing fault is £90-160 including labour.

HW light on PCB 40 flashing High

Boiler Fault Code HW light on PCB 40 flashing

Also written as HWLIGHTONPCB40FLASHING — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code HW light on PCB 40 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 detected a fault with the temperature sensor that controls your hot water, meaning it cannot accurately measure how hot the water is. (As reported on Ideal Response)

Pick your boiler brand for the HW light on PCB 40 flashing fix

Ideal HW light on PCB 40 flashing 1 model

Source

Information for the HW light on PCB 40 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