BoilerFaultCodes Fan speed too low. High
Boiler Fault Code Fan speed too low.
Also written as FANSPEEDTOOLOW — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Fan speed too low. 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 is struggling to push air through its system because the internal fan is not spinning at the required speed, which prevents it from firing up safely. (As reported on Worcester Bosch Greenstar 25CDi)
Pick your boiler brand for the Fan speed too low. fix
Source
Information for the Fan speed too low. 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 7 July 2026