audi fault code 04875 Coolant pump B

Had an issue a few months ago, where I had a leak in my coolant tank.
I added ragnal to the coolant to close the leak which it did.

A short while later I started getting an error coming up saying the coolant pump B was not working.
I have since gone to Audi who have did  a full diagnostic and they came back saying the coolant pump needed replacing,

I then bought a coolant pump from Audi to ensure I had the right part and I have had that fitted.

I am still getting the same error.

The engine is not overheating. The car still runs okay however when I am in stationary traffic for a while my oil warning light comes on telling me to check my oil level, which I know is okay.

Does anyone have any ideas what else it could be or could it be that the coolant pump just needs running In what’s your advice and thoughts? 
 

Simon