LD3 ON High

Biasi LD3 ON Fault Code

Also written as LD3ON — same fault.

The Biasi LD3 ON fault code means: your boiler has stopped working because it failed to light or detected a safety issue, causing it to shut down for protection.. It appears on 1 Biasi model 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: Lock-out - No flame / Safety thermostat / Flue temperature probe / Condensate trap full / Air pressure switch / Electronic control p.c.b.
Typical repair cost £100-350 (including labour)

DIY fix possible

Check that your gas pre-payment meter (if applicable) has creditEnsure that any external condensate drain pipes are not frozen or blockedPress and hold the reset button for 5 seconds to try and restart the boiler

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Biasi models that show the LD3 ON fault code

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

Source

Biasi LD3 ON 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