Fast flash / Not a fault code Low

Worcester Bosch Fast flash / Not a fault code Fault Code

Also written as FASTFLASHNOTAFAULTCODE — same fault.

The Worcester Bosch Fast flash / Not a fault code fault code means: your boiler is currently stuck in a manual testing mode used by engineers and needs to be switched back to its normal operating setting.. It appears on 1 Worcester Bosch model in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Service mode selected to min, press service button to return to normal.

DIY fix possible

Locate the button with a 'spanner' icon or labelled 'service'.Press the service button once to exit the testing mode.The blue light should stop flashing rapidly and return to a steady state.

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Worcester Bosch models that show the Fast flash / Not a fault code fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Worcester Bosch Fast flash / 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