BoilerFaultCodes A5:5 Low
Boiler Fault Code A5:5
Also written as A55 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code A5:5 appears across 1 boiler brand and 6 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler is currently saving energy by temporarily turning off the central heating pump because the weather outside is warm enough that your home does not need extra heat. (As reported on Viessmann Vitodens 333)
Pick your boiler brand for the A5:5 fix
Source
Information for the A5:5 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