How much does it cost to fix boiler error code 300?

Typical repair cost for the boiler 300 fault is £150-350 including labour.

300 High

Boiler Fault Code 300

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code 300 appears across 5 boiler brands and 5 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is failing to light the flame properly, which means it cannot provide heat or hot water until the ignition system is corrected. (As reported on Worcester Bosch Greenstar Utility 18/25)

Pick your boiler brand for the 300 fix

Ariston 300 1 model Ideal 300 1 model Malvern 300 1 model Navien 300 1 model Worcester Bosch 300 1 model

Source

Information for the 300 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 7 July 2026