i9 Low

Boiler Fault Code i9

Also written as I9 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code i9 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 The display is simply showing the current temperature of the water inside the boiler rather than indicating a fault. (As reported on Worcester Bosch Greenstar Heatslave II)

Pick your boiler brand for the i9 fix

Worcester Bosch i9 1 model

Source

Information for the i9 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