First timer here. Working on changing my MAF sensor and I stumbled across this piece (on the passenger side about the MAF) and it looks extremely corroded and I would love to replace this while I'm changing out the MAF sensor. It says "Motor" with an arrow pointing down. Any idea what this could be and where I could find a replacement? I have an Audi A4 1.8T year 2000.
Thanks!

-Elizabeth

 

Hi .
That looks like a one way valve, on the engine breather system.The other end should be attached to a pipe also. A new vale may possible only come with the pipe. Should be a part number on the valve or the pipe, which would help narrow it down when being looked up.

 

Thank you! I took your advice, found out it was the "Check Valve". Found it online for $8. Foreign parts near my house wanted to charge me $58. hahahaha