7 nn Low

Boiler Fault Code 7 nn

Also written as 7NN — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code 7 nn appears across 1 boiler brand and 1 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has successfully finished its heating cycle for the main zone and is currently pausing as requested. (As reported on Keston C90 / C110)

Pick your boiler brand for the 7 nn fix

Keston 7 nn 1 model

Source

Information for the 7 nn 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 27 April 2026