E04 Medium

Boiler Fault Code E04

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code E04 appears across 8 boiler brands and 30 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has lost the connection to the temperature sensor responsible for your hot water storage tank, meaning it cannot accurately monitor your hot water temperature. (As reported on Vokera Condexa Pro)

Pick your boiler brand for the E04 fix

Ariston E04 5 models Biasi E04 12 models Keston E04 4 models Potterton E04 2 models Vokera E04 2 models Warmflow E04 3 models Warmhaus E04 1 model Worcester Bosch E04 1 model

Source

Information for the E04 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