BoilerFaultCodesAriston E74 Fault Code
The Ariston E74 fault code means: your boiler's temperature sensor is sending a faulty signal, which prevents the system from accurately measuring how much heat is returning to the unit and stops it from operating.. It appears on 4 Ariston models in our database.
Technical description: Heating return temperature probe in short circuit
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Ariston models that show the E74 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Ariston E74 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