How much does it cost to fix Alpha error code 84?

Typical repair cost for the Alpha 84 fault is £120-250 including labour.

84 High

Alpha 84 Fault Code

Q: What does the Alpha 84 fault code mean?

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.

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 10 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

Typical repair cost £120-250 (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 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 27 April 2026