BoilerFaultCodesWorcester Bosch 251 Fault Code
The Worcester Bosch 251 fault code means: your boiler's internal computer is experiencing a software or logic error, preventing it from processing information correctly.. It appears on 8 Worcester Bosch models in our database.
Technical description: System fault boiler electronics / basic controller
What causes the Worcester Bosch 251 fault?
This fault occurs when the boiler's main control board experiences a fatal communication error or a failure in its internal data memory. It is usually caused by a physical components breakdown within the circuitry or an electrical surge that has corrupted the board's software. The boiler stops running because the 'brain' can no longer safely coordinate the heating process.
DIY fix possible
Press the Reset button on the front control panel once.If the code persists, turn the boiler's power switch off for 30 seconds and then back on.Ensure there has not been a recent power cut or surge in the home.
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Gas Safe Register →Worcester Bosch models that show the 251 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 251 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