A 02 High

Ariston A 02 Fault Code

Also written as A02 — same fault.

The Ariston A 02 fault code means: your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.. It appears on 3 Ariston models 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: check the pressure gauge to see if the water pressure in the appliance is 1 bar

DIY fix possible

Locate the filling loop, which is usually a flexible metal hose underneath the boiler.Open the valves on the filling loop to allow water into the system until the pressure gauge reads between 1 and 1.5 bar.Close both valves tightly to stop the flow and check that the error code has cleared.

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Ariston models that show the A 02 fault code

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

Source

Ariston A 02 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