How much does it cost to fix boiler error code F03?

Typical repair cost for the boiler F03 fault is £120-250 including labour.

F03 Medium

Boiler Fault Code F03

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 31 August 2026

Fault code F03 appears across 3 boiler brands and 3 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is having trouble reading the temperature of its internal hot water storage tank, which usually means the system needs a reset or a faulty sensor replaced. (As reported on Glow-worm Ultracom 35 Store)

Pick your boiler brand for the F03 fix

Glow-worm F03 1 model Heatline F03 1 model Viessmann F03 1 model

Source

Information for the F03 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 31 August 2026