BoilerFaultCodesAriston 7 23 Fault Code
Also written as 723 — same fault.
The Ariston 7 23 fault code means: your boiler has detected that the water temperature in one part of your heating system is higher than it should be, causing it to shut down for safety.. It appears on 6 Ariston models in our database.
Technical description: Overheating in zone 3
What causes the Ariston 7 23 fault?
This fault occurs when the boiler's sensors detect an unsafe rise in water temperature specifically within the third heating zone of your system. The most common reasons are a motorised zone valve that has failed to open, a blockage in that section of pipework, or a pump that isn't circulating the water quickly enough to carry heat away from the heat exchanger.
This issue often surfaces at the start of autumn when the heating is turned on for the first time after summer, as internal valve parts can seize up during long periods of inactivity.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Ariston models that show the 7 23 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ariston 7 23 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