d16 High

Boiler Fault Code d16

Also written as D16 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code d16 appears across 1 boiler brand and 5 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 temperature of the gases leaving your flue, meaning it has safely shut down to prevent potential overheating. (As reported on Alpha E-Tec NXS)

Pick your boiler brand for the d16 fix

Alpha d16 5 models

Source

Information for the d16 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