BoilerFaultCodesWorcester Bosch 257 Fault Code
The Worcester Bosch 257 fault code means: your boiler's internal computer has encountered a software or communication error and cannot operate properly.. It appears on 6 Worcester Bosch models in our database.
Technical description: System fault boiler electronics / basic controller
What causes the Worcester Bosch 257 fault?
This fault occurs when the boiler's main control board experiences a critical internal communication failure or a software glitch. It is usually caused by a component failure within the circuitry or an electrical surge that has corrupted the board's ability to process data. In some cases, loose or damaged wiring connections between the internal modules can also trigger this shutdown.
DIY fix possible
Locate the reset button on the front control panel.Press and hold the reset button for several seconds.Wait for the boiler to restart and monitor if the code clears.
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Gas Safe Register →Worcester Bosch models that show the 257 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 257 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