How much does it cost to fix Ariston error code UU/1?

Typical repair cost for the Ariston UU/1 fault is £90-180 including labour.

UU/1 High

Ariston UU/1 Fault Code

Q: What does the Ariston UU/1 fault code mean?

Your boiler has detected that the water leaving the unit to heat your radiators is at an incorrect temperature, which usually indicates an issue with the sensor or water flow.

Also written as UU1 — same fault.

The Ariston UU/1 fault code means: your boiler has detected that the water leaving the unit to heat your radiators is at an incorrect temperature, which usually indicates an issue with the sensor or water flow.. It appears on 3 Ariston models in our database.

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

Typical repair cost £90-180 (including labour)

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 UU/1 fault code

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

Source

Ariston UU/1 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