How can I fix my Vokera Eclipse boiler?

My Vokera Eclipse boiler display shows a flashing E and 30.

This means that there is more than 30 degrees centigrade difference in temperature between NTC1 and NTC2 - so a new pump was fitted.

This has not cured the problem however, I can overcome the problem temporarily by shutting off the upstairs heating thereby forcing all resources to the living area.

Can anyone help please?