BoilerFaultCodesWhat the manual says
Manufacturer manualA flame is detected after the gas has been switched off.
From this model's manual
Verified against the Worcester Bosch Greenstar 25 He Combi installation & service manual, page 43.
What causes this fault?
This fault occurs when the boiler's sensors detect heat or a residual flame signal even though the gas valve has been commanded to close. The most common reason is a gas valve that is physically leaking or failing to shut tightly, or a faulty sensor/circuit board that is incorrectly 'seeing' a flame that isn't really there.
Engineer required
This is a emergency severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register →
Boiler cover options
Avoid the next call-out bill
A cover plan would handle faults like FA: no call-out fees, no surprise bills.
Approved partner
Get a quote →
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Affiliate links. We may earn a commission at no extra cost to you.