12 High

Biasi 12 Fault Code

The Biasi 12 fault code means: your boiler has detected a problem with the sensor that monitors the temperature of the water coming back from your radiators, preventing it from heating your home safely.. It appears on 6 Biasi models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Return NTC probe failure.
Typical repair cost £90-160 (including labour)

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 12 fault code

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

Source

Biasi 12 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