High
L01 on Biasi Advance Plus 16S 25S 30S

Your boiler has detected that the water inside the unit is getting too hot while it is trying to heat your tap water, so it has shut down to prevent damage.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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.

What the manual says

Manufacturer manual

Primary circuit temp. limit during D.h.w. operation

From this model's manual
Verified against the Biasi Activ A installation & service manual, page 13.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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