Boiler Fault Code d.93

Also written as D93 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026

Fault code d.93 appears across 3 boiler brands and 23 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler's electronic control board is reporting a mismatch or identification error, which often indicates that the main computer chip has failed to recognise the specific settings for your boiler model. (As reported on Heatline Monza)