BoilerFaultCodesWorcester Bosch 6a Fault Code
Also written as 6A — same fault.
The Worcester Bosch 6a fault code means: your boiler has detected that the exhaust gases are getting too hot and has shut down as a safety precaution to prevent damage.. It appears on 3 Worcester Bosch models in our database.
Technical description: Type a Flue overheat thermostat (Screw thread)
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 6a fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 6a 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