Boiler Fault Code 1 to 24

Also written as 1TO24 — same fault.

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

Fault code 1 to 24 appears across 1 boiler brand and 3 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 a general internal fault that prevents it from operating, and because these codes cover a wide variety of issues, a qualified engineer must investigate. (As reported on Ideal Concord Cxdi)