Boiler Fault Code i20

Also written as I20 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026

Fault code i20 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 Your boiler is displaying its internal software version, which indicates a computer communication error rather than a physical breakdown, but the unit will not operate while this message is present. (As reported on Worcester Bosch Greenstar Heatslave II)