2 05 Medium

Ariston 2 05 Fault Code

Also written as 205 — same fault.

The Ariston 2 05 fault code means: your boiler is having trouble measuring the temperature of the water coming from your solar thermal system or incoming supply, which can affect how your hot water is heated.. It appears on 8 Ariston models in our database.

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description: DHW In Probe Open Circuit (Solare temp. probe)
Typical repair cost £90-160 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →

Ariston models that show the 2 05 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Ariston 2 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