How much does it cost to fix boiler error code E004?

Typical repair cost for the boiler E004 fault is £150-300 including labour.

E004 High

Boiler Fault Code E004

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code E004 appears across 1 boiler brand and 6 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has detected a flame when it shouldn't be burning, suggesting a sensor error or a gas valve issue that prevents the unit from starting safely. (As reported on Navien NCB-28LDWE)

Pick your boiler brand for the E004 fix

Navien E004 6 models

Source

Information for the E004 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