BoilerFaultCodes i1 Low
Boiler Fault Code i1
Also written as I1 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code i1 appears across 1 boiler brand and 1 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning This code is not an actual fault; it is simply showing your boiler's current operating status or mode of activity while it is running normally. (As reported on Worcester Bosch Greenstar Heatslave II)
Pick your boiler brand for the i1 fix
Source
Information for the i1 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 27 April 2026