425 Low

Boiler Fault Code 425

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code 425 appears across 2 boiler brands and 2 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is having trouble connecting to the internet to set its internal clock, which may disrupt your heating schedules. (As reported on Viessmann Vitodens 100-W B1GA)

Pick your boiler brand for the 425 fix

ECA 425 1 model Viessmann 425 1 model

Source

Information for the 425 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