77 Emergency

Alpha 77 Fault Code

The Alpha 77 fault code means: your boiler has detected a problem with the internal mechanism that controls the gas supply, meaning it has safely shut itself down to prevent unsafe operation.. It appears on 6 Alpha models in our database.

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now. This fault can be dangerous if ignored.

Technical description: Anomaly on the gas valve control
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 77 fault code

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

Source

Alpha 77 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 7 July 2026