How much does it cost to fix Ariston error code 118?

Typical repair cost for the Ariston 118 fault is £80-220 including labour.

118 High

Ariston 118 Fault Code

Q: What does the Ariston 118 fault code mean?

Your boiler has detected that the water pressure is too high, often caused by the filling loop being left open or a fault in the expansion system.

The Ariston 118 fault code means: your boiler has detected that the water pressure is too high, often caused by the filling loop being left open or a fault in the expansion system.. It appears on 1 Ariston model in our database.

Technical description: All Boilers

Typical repair cost £80-220 (including labour)

DIY fix possible

Check that the filling loop valves are tightly closedBleed water from a radiator using a bleed key to reduce the system pressureMonitor the pressure gauge to ensure it returns to between 1 and 1.5 barReset the boiler once the pressure is stabilised

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Ariston models that show the 118 fault code

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

Alteas One Repair: £80-220

Source

Ariston 118 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