BoilerFaultCodesWorcester Bosch 2963 B Fault Code
Also written as 2963B — same fault.
The Worcester Bosch 2963 B fault code means: your boiler has detected an unusual temperature reading because a sensor or its wiring is not communicating correctly with the main control unit.. It appears on 5 Worcester Bosch models in our database.
Technical description: Signal from flow and heat exchanger temperature sensor outside the permissible range – the connecting lead needs connecting correctly
What causes the Worcester Bosch 2963 B fault?
This fault occurs when the boiler's central control board receives an impossible temperature reading from the internal sensors. This is usually caused by a loose connection in the internal wiring or a sensor that has physically failed, meaning the boiler can no longer safely monitor the water temperature inside the heat exchanger.
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 2963 B fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 2963 B 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 Greenstar 2000 manual (PDF)
- Worcester Bosch Greenstar 4000 manual (PDF)
- Worcester Bosch Greenstar 8000 Life & Style manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026