I went to the store and got a hose, the only one they had was a fuel hose. Because it was super ridig, I couldn't stretch it and used a good piece of the old hose to connect it to the back (there's suction at that port when the car is running).
I tried to take the best picture I could.
Blue hose is the new one I installed.
I'm not sure what that hose is exactly.
I tried looking on realoem but couldn't find it

In any case I've connected it back


I found another hose, it has no suction when the car is running. I have no clue where it's supposed to.go either


Did a test of the cluster panel.
Don't E53 have check engine light at all?