How much does it cost to fix boiler error code H4?

Typical repair cost for the boiler H4 fault is £120-190 including labour.

H4 High

Boiler Fault Code H4

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code H4 appears across 2 boiler brands and 8 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 the temperature of the exhaust gases, causing the system to shut down as a safety precaution. (As reported on Ideal Mexico HE)

Pick your boiler brand for the H4 fix

Ideal H4 4 models Worcester Bosch H4 4 models

Source

Information for the H4 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