BoilerFaultCodesWhat the manual says
Manufacturer manualBurner lockout indicated by the control panel LCD display; burner fails to establish a normal firing pattern or flame failure occurs.
What causes this fault?
This fault happens because the burner has failed to establish a flame after several attempts, causing the boiler to shut down for safety. The most common cause is simply a lack of fuel reaching the burner, either because the oil tank is empty or there is a blockage in the supply line. It can also be caused by a dirty sensor that can no longer 'see' the flame or a worn-out nozzle that isn't spraying fuel correctly.
This fault is particularly common during the first cold snap of autumn when oil levels may be low following the summer or when thickened 'waxing' occurs in the oil during extremely cold winter spells.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Avoid the next call-out bill
A cover plan would handle faults like 9F855: no call-out fees, no surprise bills.
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