BoilerFaultCodesWorcester Bosch Flash 8 times per second Fault Code
Also written as FLASH8TIMESPERSECOND — same fault.
The Worcester Bosch Flash 8 times per second fault code means: your boiler has been left in a service mode used for testing, meaning it is currently stuck running at a constant power level instead of operating normally.. It appears on 1 Worcester Bosch model in our database.
Technical description: GV mode switch. Gas Valve mode switch on min or max.
What causes the Worcester Bosch Flash 8 times per second fault?
This fault occurs when a manual switch inside the boiler has been left in a testing position, usually after a service or repair. It physically prevents the boiler from adjusting its flame size automatically, meaning the system cannot regulate the heat for your taps or radiators. While it is often just a switch left in the wrong position, it can also happen if the main control board becomes faulty and misreads the signal.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Worcester Bosch models that show the Flash 8 times per second fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch Flash 8 times per second 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