BoilerFaultCodesAriston Insufficient water pressure Fault Code
Also written as INSUFFICIENTWATERPRESSURE — same fault.
The Ariston Insufficient water pressure fault code means: your boiler has stopped because the water pressure inside your heating system has dropped too low to operate safely.. It appears on 2 Ariston models in our database.
Technical description: INSUFFICIENT SYSTEM PRESSURE: In the event of insufficient water pressure in the heating system (less than 0.4 bar), a safety device will shutdown the boiler.
DIY fix possible
Locate the external filling loop, which is usually a small silver braided hose with one or two valves underneath the boiler.Open the valves slowly to allow mains water into the system until the pressure gauge on the front of the boiler reads between 1.0 and 1.5 bar.Close the valves tightly to stop the flow and ensure the loop is disconnected if it is a detachable type.
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Ariston models that show the Insufficient water pressure fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ariston Insufficient water pressure 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 7 July 2026