BoilerFaultCodesAriston E02 Fault Code
The Ariston E02 fault code means: your boiler has stopped working because the water pressure inside the system is currently too low to operate safely.. It appears on 5 Ariston models in our database.
Technical description: Low water pressure switch does not close. Check if there is air in the system, check the main circuit flow switch operation, check the pressure on the water gauge and fill system to 1 bar.
DIY fix possible
Check the pressure gauge on the front of the boiler; if it reads below 1 bar, your system needs topping up.Locate the external filling loop (a silver braided hose with one or two valves) connected to the pipework underneath the boiler.Open the valves slowly to allow water into the system until the gauge reaches 1.5 bar, then ensure the valves are tightly closed.
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Gas Safe Register →Ariston models that show the E02 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ariston E02 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