05 Low

Ariston 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 4 Ariston models in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

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 27 April 2026