BoilerFaultCodesAlpha 84 Fault Code
The Alpha 84 fault code means: your boiler has detected that it is not receiving enough gas to work properly, so it has lowered its performance to keep itself safe while it runs in a limited emergency mode.. It appears on 6 Alpha models in our database.
Technical description: Combustion fault. Boiler operating in reduced output mode. A low supply pressure is detected on the gas line. As a result the appliance output is limited and the error code is displayed
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 84 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Alpha 84 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