BoilerFaultCodes 01 to 99 Medium
Boiler Fault Code 01 to 99
Also written as 01TO99 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 01 to 99 appears across 1 boiler brand and 7 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has stored a record of a previous error that caused it to stop working, and it may need a professional to clear the history or investigate the underlying cause. (As reported on Chaffoteaux Serelia 24 MFFI)
Pick your boiler brand for the 01 to 99 fix
Source
Information for the 01 to 99 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