BoilerFaultCodesWorcester Bosch i15 Fault Code
Also written as I15 — same fault.
The Worcester Bosch i15 fault code means: your boiler is simply displaying the current outdoor temperature because a weather sensor is connected, which is a normal status reading rather than a fault.. It appears on 1 Worcester Bosch model in our database.
Technical description: Out door temperature - This is the out door temperature displayed in real time (rounded to 0.5°C units). Only available if a Weather Compensation sensor has been fitted and Weather Compensation is active.
DIY fix possible
No action is required as this is a status notification, not an error.Check your boiler display manual if you wish to toggle the default display view back to the target room temperature.
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Worcester Bosch models that show the i15 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch i15 fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026