BoilerFaultCodes 2 01 Medium
Boiler Fault Code 2 01
Also written as 201 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 2 01 appears across 1 boiler brand and 2 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler is struggling to detect the temperature of your hot water supply because a connection to one of its internal sensors has been lost. (As reported on Ariston Clas One)
Pick your boiler brand for the 2 01 fix
Source
Information for the 2 01 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