Boiler Fault Code d19

Also written as D19 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026

Fault code d19 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 is displaying an internal software diagnostic screen, which usually means the system is performing a self-check or has encountered a minor glitch in its display settings. (As reported on Alpha E-Tec S)