How much does it cost to fix boiler error code 100 B?

Typical repair cost for the boiler 100 B fault is £80-150 including labour.

100 B High

Boiler Fault Code 100 B

Also written as 100B — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code 100 B 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 is not detecting the necessary water pressure to operate safely and will not provide heating or hot water until this is corrected. (As reported on Sime Format B Combi)

Pick your boiler brand for the 100 B fix

Sime 100 B 1 model

Source

Information for the 100 B 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