0A5 High

Alpha 0A5 Fault Code

The Alpha 0A5 fault code means: your boiler has detected that the internal fan responsible for safely removing exhaust gases is not spinning at the correct speed, causing the system to stop for safety reasons.. It appears on 3 Alpha models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Fan speed fault. Check flue and ventilation. Check air inlet manifold and pipe. Check for fan damage/fault. Check fan wire connections.

What causes the Alpha 0A5 fault?

This fault occurs when the boiler's control system loses the ability to manage or monitor the speed of the internal fan. The most common reason is a mechanical failure within the fan motor or a communication error on the circuit board, meaning the boiler cannot safely expel exhaust gases. As a result, the system shuts down as a vital safety precaution to prevent dangerous fumes from building up.

Typical repair cost £150-350 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Alpha models that show the 0A5 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Alpha 0A5 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