How much does it cost to fix boiler error code 404?

Typical repair cost for the boiler 404 fault is £450-£700 including labour.

404 High

Boiler Fault Code 404

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code 404 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's main control computer has developed a serious internal error and can no longer manage the heating process safely. (As reported on Viessmann Vitodens 100-W B1GA)

Pick your boiler brand for the 404 fix

Viessmann 404 1 model

Source

Information for the 404 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