Genus a77 fault?

Keep getting a77 fault on micro genus boiler. The condensate trap keeps filling. Thanks Nick for you earlier reply. I have checked the plastic flexible tube leading from the trap outside, this is clear. The trap fills when the heating is on and you then run hot water. It fills quickly and when emptied you can run a bath but the trap fills again when water next used. The water in the trap is warm. I want to avoid call out fee if the problem is easily sorted by myself. The water pressure is around 2 1/2 bar.