LP Low

Boiler Fault Code LP

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code LP appears across 3 boiler brands and 11 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has been accidentally switched into a specific testing mode used by engineers to check emissions, which prevents it from heating your home normally. (As reported on Biasi Activ A)

Pick your boiler brand for the LP fix

Biasi LP 8 models Johnson Starley LP 1 model Unical LP 2 models

Source

Information for the LP 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