20 + High

Biasi 20 + Fault Code

Also written as 20 — same fault.

The Biasi 20 + fault code means: your boiler has detected an internal electrical failure with the control board that operates the gas valve, causing the system to shut down for safety.. It appears on 4 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: EVG lockout (valve piloting hardware failure).
Typical repair cost £180-350 (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 20 + fault code

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

Source

Biasi 20 + 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