BoilerFaultCodesWorcester Bosch Not a fault code Fault Code
Also written as NOTAFAULTCODE — same fault.
The Worcester Bosch Not a fault code fault code means: your boiler is currently in a manual testing mode used by engineers, which is why it has stopped operating normally.. It appears on 1 Worcester Bosch model in our database.
Technical description: 2 pulses | No light | Service mode selected to min, press service button to return to normal.
DIY fix possible
Locate the blue 'Service' button on the front control panel.Press and release the service button once.Observe the boiler to ensure it returns to standard operation and the pulsing light pattern stops.
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Worcester Bosch models that show the Not a fault code fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch Not a fault code 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