How much does it cost to fix Alpha error code B Flashing?

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

B Flashing High

Alpha B Flashing Fault Code

Q: What does the Alpha B Flashing fault code mean?

Your boiler has detected that it is getting too hot and has automatically shut down to prevent any damage or safety hazards.

Also written as BFLASHING — same fault.

The Alpha B Flashing fault code means: your boiler has detected that it is getting too hot and has automatically shut down to prevent any damage or safety hazards.. It appears on 5 Alpha models in our database.

Technical description: Overheat thermostat has operated.

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 B Flashing fault code

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

Source

Alpha B Flashing 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