How much does it cost to fix Ariston error code UU/2?

Typical repair cost for the Ariston UU/2 fault is £120-£350 including labour.

UU/2 High

Ariston UU/2 Fault Code

Q: What does the Ariston UU/2 fault code mean?

Your boiler has detected that the water returning from your radiators is at an unusual temperature, which usually means the water isn't flowing through the system correctly.

Also written as UU2 — same fault.

The Ariston UU/2 fault code means: your boiler has detected that the water returning from your radiators is at an unusual temperature, which usually means the water isn't flowing through the system correctly.. It appears on 3 Ariston models in our database.

Technical description: Return temperature of the heating circuit (C°)

Typical repair cost £120-£350 (including labour)

DIY fix possible

Check that all radiator valves are fully openEnsure the boiler pressure gauge is between 1 and 1.5 barGently bleed your radiators to remove any trapped air

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Ariston models that show the UU/2 fault code

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

Source

Ariston UU/2 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