BoilerFaultCodesAriston A02 Fault Code
The Ariston A02 fault code means: your boiler has stopped working because the water pressure is too low, meaning there isn't enough water inside the system to operate safely.. It appears on 10 Ariston models in our database.
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 (usually a silver braided hose with small taps) underneath the boiler.Slowly open the taps until you hear the water flowing and watch the pressure gauge needle move.Close the taps firmly once the pressure gauge reaches between 1 and 1.5 bar.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Avoid the next call-out bill
A cover plan would handle faults like A02: no call-out fees, no surprise bills.
Affiliate links. We may earn a commission at no extra cost to you.
Ariston models that show the A02 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ariston A02 fault code information on this page is sourced and cross-checked against the official Ariston service / installation manuals for each affected model.
- Ariston ACO 32 MFFI manual (PDF)
- Ariston Genus 24 Rffi manual (PDF)
- Ariston Micro Condens manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026