350 Medium

Boiler Fault Code 350

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code 350 appears across 4 boiler brands and 5 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 communicating with its external water storage tank, preventing it from knowing how much hot water is available. (As reported on ECA FELiS FL 50 HM)

Pick your boiler brand for the 350 fix

Ariston 350 1 model ECA 350 1 model Viessmann 350 1 model Worcester Bosch 350 2 models

Source

Information for the 350 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