n4 High

Boiler Fault Code n4

Also written as N4 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code n4 appears across 2 boiler brands and 2 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 an issue with the water flow or pressure sensor, meaning it has temporarily stopped working to protect the internal components. (As reported on Glow-worm Jaguar Combi)

Pick your boiler brand for the n4 fix

Glow-worm n4 1 model Protherm n4 1 model

Source

Information for the n4 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