348 Emergency

Boiler Fault Code 348

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code 348 appears across 4 boiler brands and 12 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 to get enough fresh air for safe combustion because the ventilation in the room where it is installed is blocked, insufficient, or obstructed. (As reported on Grant Vortex Eco)

Pick your boiler brand for the 348 fix

ECA 348 1 model Grant 348 6 models Viessmann 348 1 model Worcester Bosch 348 4 models

Source

Information for the 348 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