BoilerFaultCodesWorcester Bosch 208 Fault Code
The Worcester Bosch 208 fault code means: your boiler is currently set to a manual testing mode used by engineers to check emissions, which prevents it from operating normally.. It appears on 15 Worcester Bosch models in our database.
Technical description: Chimney sweep demand
What causes the Worcester Bosch 208 fault?
This code appears when the 'Chimney Sweep' mode has been manually activated on the boiler's control panel. It is a setting used by engineers during a service to force the boiler into maximum or minimum output for emissions testing, which overrides your normal heating and hot water settings. If this has appeared unexpectedly, it is usually because the button was pressed by accident or the mode was not exited after a recent service.
This code is frequently seen during the autumn and winter months when annual service visits and safety checks are most commonly scheduled.
DIY fix possible
Locate the 'Chimney Sweep' button (icon looks like a brush) on the touch screen display.Press and hold the button for approximately 3 to 5 seconds.The display should return to the standard temperature screen once the mode is deactivated.
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Worcester Bosch models that show the 208 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 208 fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.
- Worcester Bosch 24/28/35 CDi MkII manual (PDF)
- Worcester Bosch 26 CDi Xtra manual (PDF)
- Worcester Bosch Greenstar 1000 manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026