How much does it cost to fix boiler error code b33?

Typical repair cost for the boiler b33 fault is £140-£260 including labour.

b33 High

Boiler Fault Code b33

Also written as B33 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code b33 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 an issue with the sensor that monitors water movement, meaning it cannot properly manage the temperature or flow of your heating. (As reported on Johnson Starley Warmcair DW)

Pick your boiler brand for the b33 fix

Johnson Starley b33 1 model

Source

Information for the b33 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