Combi cutting out error e168

[Sarahf]

Hi,

I have a combi duo tec he 24. It has recently started cutting out when I put the heating one after about 2minutes.

It comes up with error 168 which when I looked on net it said it was the pcb, however when I have done a bit of experimenting with the heat of the radiators I have found that if I set the radiators to a low temperature it doesn't come up with the error message or anything! But when I turn the heat of the radiators up again (as when it is low it's not heating the place up at all) it comes up with the error message again!

Can anyone help please? I'm hoping it's not the pcb as read it is expensive and as the boiler is just out of warranty I don't have insurance!!

Thanks
Sarah