BoilerFaultCodesAlpha 0A31 Fault Code
The Alpha 0A31 fault code means: your boiler has detected that a temperature reading from its internal water system is not what it expects, meaning it has safely shut down to prevent damage.. It appears on 3 Alpha models in our database.
Technical description: Flow sensor out of range. Sensor measures a temperature outside normal working range.
What causes the Alpha 0A31 fault?
This fault occurs when the boiler's internal computer receives a temperature reading that is physically impossible or outside of its safety limits. It is usually caused by a chemical failure inside the flow sensor itself or a loose connection in the wiring that interrupts the electrical signal. Because the boiler can no longer accurately monitor how hot the water is, it shuts down to prevent the system from overheating.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Alpha models that show the 0A31 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Alpha 0A31 fault code information on this page is sourced and cross-checked against the official Alpha service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026