1 second ON 1 second OFF Low

Biasi 1 second ON 1 second OFF Fault Code

Also written as 1SECONDON1SECONDOFF — same fault.

The Biasi 1 second ON 1 second OFF fault code means: your boiler has detected that the temperature is low and is running its internal protection mode to prevent the pipes from freezing.. It appears on 5 Biasi models in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Anti-freeze system active. C.h. operation or D.h.w. operation

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Biasi models that show the 1 second ON 1 second OFF fault code

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

Source

Biasi 1 second ON 1 second OFF 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 7 July 2026