What do the letters SE flashing in display window mean?

if boiler has been serviced within 12 months, you can clear it yourself (it's just a timer). If it has not been serviced in last 12 months, arrange for it to be done as it's especially important for condensing boilers.

To clear SE:

Press spanner button for about 10sec unitl it glows orange
You will see 1.A in display
Press Eco repeatedly until display shows 5A
Press Chimney Sweep button (man with ladder) once.
Button will glow and 00 appears on display
Press Eco once
Press and hold Chimney Sweep until [] appears on display, then let go
Press spanner once, it will stop glowing and the display will go back to normal (shows flow temp) and SE will be gone.

Bunslinger
April 2009

Its telling you that the boiler has run for a certain length of time, and that it is about due for a service. Its not showing a fault.

John
April 2009