How much does it cost to fix boiler error code L3?

Typical repair cost for the boiler L3 fault is £120-250 including labour.

L3 High

Boiler Fault Code L3

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code L3 appears across 2 boiler brands and 2 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has detected that hot water is not circulating properly around your radiators, meaning your heating system cannot function correctly. (As reported on Biasi Concept 400 20 1 Mfs)

Pick your boiler brand for the L3 fix

Baxi L3 1 model Biasi L3 1 model

Source

Information for the L3 fault code is sourced from the official service / installation manual for each model that displays it. Read more about how we source fault codes →

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026