How much does it cost to fix boiler error code H.03 -.00?

Typical repair cost for the boiler H.03 -.00 fault is £90-180 including labour.

H.03 -.00 High

Boiler Fault Code H.03 -.00

Also written as H0300 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code H.03 -.00 appears across 1 boiler brand and 24 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has stopped working because its internal sensors or control system are struggling to talk to each other correctly. (As reported on Baxi 200 / 400 Combi)

Pick your boiler brand for the H.03 -.00 fix

Baxi H.03 -.00 24 models

Source

Information for the H.03 -.00 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