99 High

Alpha 99 Fault Code

The Alpha 99 fault code means: your boiler has detected a general internal fault that has caused it to stop working for safety reasons.. It appears on 4 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: General block A boiler anomaly has been detected
Typical repair cost £150-300 (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 99 fault code

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

Source

Alpha 99 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 31 August 2026