103 High

Ariston 103 Fault Code

The Ariston 103 fault code means: your boiler is likely having trouble circulating water properly, which is causing it to overheat and shut down for safety.. It appears on 1 Ariston model in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: All Boilers
Typical repair cost £150-350 (including labour)

DIY fix possible

Check that your system pressure is between 1 and 1.5 bar on the display.Ensure all radiator valves are fully open to allow water to flow.Attempt to reset the boiler once pressure and valves are checked.

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Ariston models that show the 103 fault code

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

Source

Ariston 103 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