FL Medium

Biasi FL Fault Code

The Biasi FL fault code means: your boiler is notifying you that the water pressure has dropped too low and the system needs to be topped up.. It appears on 1 Biasi model in our database.

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description: Filling request: The boiler works regularly and the display shows all the icons, but the signal FL is flashing every 1 sec.
Typical repair cost £0-80 (including labour)

DIY fix possible

Locate the filling loop valves underneath the boiler.Slowly open both valves to allow water into the system.Close both valves tightly once the pressure gauge reaches between 1 and 1.5 bar.

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Biasi models that show the FL fault code

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

Source

Biasi FL fault code information on this page is sourced and cross-checked against the official Biasi service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026