BoilerFaultCodesTechnical description
Safety switch-off – fault in flame detection
What causes this fault?
This fault occurs when the boiler's internal computer senses a flame signal at a time when the burner should be switched off. The most common reason is that the flame sensing component is covered in carbon deposits or the main gas valve is leaking and allowing a small amount of gas to burn when it shouldn't. In some cases, an electrical fault on the control board can cause it to 'see' a flame that isn't actually there.
This fault is more common during the winter months when the boiler is working harder, as increased usage can lead to a quicker buildup of debris on the sensing electrodes.
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.