BoilerFaultCodesAriston 05 Fault Code
The Ariston 05 fault code means: your boiler is simply performing a routine automatic safety check to prevent its internal parts from freezing up during cold weather.. It appears on 5 Ariston models in our database.
Technical description: anti-freeze - pump only: the circulating pump operates for one minute and the diverter valve switches every 23 hours. The pump starts at 8°C.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Ariston models that show the 05 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ariston 05 fault code information on this page is sourced and cross-checked against the official Ariston service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026