Can the AOS vent line cause vacuum leak?
 

Title says it all - trying to troubleshoot a vacuum leak in a '97. Newish AOS that is functioning fine (I know it is not the problem) could the AOS vent line that connects the top of the AOS to the intake / throttle body, if not properly sealed, cause a vacuum leak at low speed that would trigger a CEL? Could it happen due to an ill fitting o ring on the end of the vent line?

Thx-

Yes there are o-rings in in both ends to seal off both residual oil mist and air.

Wrap some self sealing tape around the connection and see if the behavior changes.

Yes. I Had vacuum issues when I could not get a good seal on TB side of hose. Should replace with new AOS. Cheap part

I just changed this part. It's only $28.00 and easy to remove and install.
Any leak from this hose will effect the way your engine run.