35 High

Boiler Fault Code 35

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code 35 appears across 8 boiler brands and 34 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler's internal control module is failing to communicate with the fan, causing the system to shut down immediately after trying to start. (As reported on Ideal Maximiser SE)

Pick your boiler brand for the 35 fix

Alpha 35 5 models Atag 35 1 model Ferroli 35 3 models Halstead 35 8 models Ideal 35 1 model Vaillant 35 1 model Viessmann 35 12 models Vokera 35 3 models

Source

Information for the 35 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