BoilerFaultCodesWorcester Bosch 8 flashes Fault Code
Also written as 8FLASHES — same fault.
The Worcester Bosch 8 flashes fault code means: your boiler has tried to start but could not detect a flame, meaning it cannot heat your water or radiators and has shut down for safety.. It appears on 3 Worcester Bosch models in our database.
Technical description: Flame not detected.
DIY fix possible
Check if other gas appliances in your home (like a hob) are working to ensure gas is reaching the propertyCheck that your gas meter has credit if you have a pre-payment meterIn freezing weather, check if your external condensate pipe is frozen and thaw it with warm waterPress and hold the 'Reset' button for five seconds
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Avoid the next call-out bill
A cover plan would handle faults like 8 flashes: no call-out fees, no surprise bills.
Affiliate links. We may earn a commission at no extra cost to you.
Worcester Bosch models that show the 8 flashes fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 8 flashes fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.
- Worcester Bosch Greenstar 25CDi manual (PDF)
- Worcester Bosch Greenstar 35 CDi manual (PDF)
- Worcester Bosch Greenstar 42CDi manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026