396 High

Boiler Fault Code 396

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code 396 appears across 2 boiler brands and 7 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is struggling because the ventilation system providing fresh air to the unit is insufficient or blocked, preventing safe and efficient operation. (As reported on Grant Vortex Eco)

Pick your boiler brand for the 396 fix

Grant 396 6 models Viessmann 396 1 model

Source

Information for the 396 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