How much does it cost to fix boiler error code 204?

Typical repair cost for the boiler 204 fault is £150-300 including labour.

204 Emergency

Boiler Fault Code 204

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 31 August 2026

Fault code 204 appears across 5 boiler brands and 16 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is detecting a flame inside the unit before it has actually commanded the gas to turn on, which suggests a faulty safety sensor or an internal component failing to shut off properly. (As reported on Keston C30 / C35)

Pick your boiler brand for the 204 fix

Chaffoteaux 204 1 model Ideal 204 1 model Keston 204 2 models Myson 204 1 model Worcester Bosch 204 11 models

Source

Information for the 204 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 31 August 2026