Worcester Bosch 808 Fault Code
The Worcester Bosch 808 fault code means: your boiler is struggling to accurately measure the temperature of the water used for your taps and shower, which will likely result in your hot water not working correctly.. It appears on 5 Worcester Bosch models in our database.
Technical description: A7 Domestic hot water sensor defect
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Worcester Bosch models that show the 808 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 808 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 Greenstar 12i System manual (PDF)
- Worcester Bosch Greenstar 28CDi manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026