BoilerFaultCodesWorcester Bosch 259 Fault Code
The Worcester Bosch 259 fault code means: your boiler's internal computer has encountered a software or communication error and can no longer control the heating process.. It appears on 8 Worcester Bosch models in our database.
Technical description: System fault boiler electronics / basic controller
What causes the Worcester Bosch 259 fault?
This fault occurs when the boiler's main control board loses the ability to communicate with the internal software or the display screen unit. It is typically caused by a critical hardware failure within the electronics or a corrupted data link between the internal components. In most cases, the central processor has failed to perform its safety checks, forcing the system to shut down for protection.
DIY fix possible
Locate the reset button on the boiler's front control panel.Press and hold the reset button for three seconds until the display changes.Wait for the boiler to complete its restart sequence to see if the error clears.
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Gas Safe Register →Worcester Bosch models that show the 259 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 259 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