While you wait for answers, we may have found some information which could help you.
Click here for Boiler Thermostat FaultHow to replace Potterton EP 3002 with EP 2?
My potterton boiler keeps losing water pressure and condens?
E133?
Potterton Perfoma 24. Hot water works fine No heating?
Potterton Prima 60F- can you start it manually?
Potterton heatmax combi?