BoilerFaultCodes 1-A3 Low
Boiler Fault Code 1-A3
Also written as 1A3 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 1-A3 appears across 1 boiler brand and 1 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler's heating power has been manually limited to a lower setting, which might prevent your home from reaching your desired temperature properly. (As reported on Worcester Bosch Greenstar 8000 Life/Style)
Pick your boiler brand for the 1-A3 fix
Source
Information for the 1-A3 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