BoilerFaultCodesWorcester Bosch 8.C Fault Code
Also written as 8C — same fault.
The Worcester Bosch 8.C fault code means: your boiler has detected an internal communication error between its electronic control components and is unable to start for safety reasons.. It appears on 1 Worcester Bosch model in our database.
Technical description: GFA status (not applicable)
What causes the Worcester Bosch 8.C fault?
This fault occurs when the boiler's internal computer system loses the ability to talk to its electronic components. It is usually caused by a physical break in the internal wiring or a critical failure of the main printed circuit board, which prevents the boiler from performing its safety checks.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Worcester Bosch models that show the 8.C fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 8.C 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 27 April 2026