Potterton Ultra2 shuts off after 10 seconds

[pottertonultra2]

I have a poterton ultra 2 gas boiler that is not firing up this morning. When the boiler was switched on, it ran for about 10 seconds and then switched off. There was a flame and the fan is working..everything seems fine then it shuts off and will not come back on. Water pressure is it usual elev of 1.5bar.

I have left for a couple of hours and tried again. The lockout light is now on. I can hear the fan working when I switch it on but there is no flame and the boiler does not ignite.

There was recent problem with the fan (6 weeks ago) where the fan was ceased. After using WD40, it ran freely and is OK since. the fan still rotates freely.

Any feedback would be much appreciated.

 

[LUNAT]

HI


can be many things
aps
pcb
fan coil
hw/ch sensor