Vokera mynute 24m natural gas boiler?

Hi all, I have a vokera Mynute gas boiler and it wont heat the water above 30-40 deg, I did notice that the bar pressure is quite low (o to .5 bar) before ti was 1.5 to 2 bar and was wondering if this is the problem. The boiler does go through all the stages of lighting up but cuts out when the water reaches 30-40 deg and I would appreciate it if someone could tell me how to fix this problem.
Thanks jp