n3 High

Boiler Fault Code n3

Also written as N3 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code n3 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 sensor that monitors the water temperature or flow, causing the system to stop working correctly as a safety precaution. (As reported on Glow-worm Jaguar Combi)

Pick your boiler brand for the n3 fix

Glow-worm n3 1 model Protherm n3 1 model

Source

Information for the n3 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