Technical description
Final fault code (Refer to section 7.11)
What causes this fault?
This fault occurs when the boiler tries to light the burner but fails to detect a stable flame after several attempts. The most common reasons include a lack of gas supply to the unit, worn-out ignition parts that can no longer create a spark, or a dirty sensor that cannot 'see' the flame even when it is lit.
This fault is more common during extreme cold spells, as external gas meters can occasionally freeze or supply pressures can drop when demand on the local grid is at its peak.
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.