Vital Energi HIU not providing heating

[FoRiS HeAtInG]

Hi there, I am currently trying to rectify a fault with a Vital Energi Heat Interface Unit (HIU) inside a new build flat, the pump inside is a Grundfos Alpha 2L and shows that power is going to it as it lights up green on all the settings although when changing the speeds it doesn't sound like the propeller is changing also, the heat meter inside is a sharky and shows the fault message E---7---

Any ideas?

Thanks