BoilerFaultCodesWorcester Bosch Flashing light Fault Code
Also written as FLASHINGLIGHT — same fault.
The Worcester Bosch Flashing light fault code means: your boiler has failed to light the gas or cannot stay lit, meaning your heating and hot water have stopped working.. It appears on 2 Worcester Bosch models in our database.
Technical description: Flame failure
What causes the Worcester Bosch Flashing light fault?
This fault occurs when the boiler's control board fails to detect a flame after several attempts to fire up. The most common reasons are a lack of gas reaching the burner, dirty internal probes that can no longer 'see' the flame, or a faulty ignition lead that isn't providing the spark needed to start the combustion process.
This fault often appears during the first cold snap of autumn when a boiler that has been idle all summer is suddenly forced to work at high capacity.
DIY fix possible
Check if your gas supply is active by testing another gas appliance like a hob.Ensure your credit is topped up if you have a pre-payment gas meter.Press the reset button on the boiler control panel for 5 seconds.
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Gas Safe Register →Worcester Bosch models that show the Flashing light fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch Flashing light 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