Low
i22 on Worcester Bosch Greenstar Heatslave II

Your boiler is displaying a specific tracking code that identifies its power configuration, which usually appears after an internal control module has been replaced or reset.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

HCM number - HCM last 3 digits displayed: 391 = 12/18 kW, 390 = 18/25 kW, 301 = 25/32 kW

From this model's manual
Verified against the Worcester Bosch Greenstar Heatslave Ii installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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