[gsmiller]

I've never really quite understood the whole AOS system so please excuse my ignorance in this question.

I have a breather hose related to the AOS that is leaking oil onto the right side of my engine. My mechanic said that as the leak worsens, it will likely cause a CEL due to vacuum leak. Can someone explain how this would be? My basic understanding is that clean air flows into the AOS device and into the crankcase (from somewhere?) and the polluted air in the case flows out, has the oil separated out and is sent back into the intake. I'd like to better understand the system but can't find any information out there.

My assumption here is that the leaking hose is pulling air from the crankcase into the intake, and that the leak would allow excess air in creating an overly lean mixture and triggering a CEL... but that's just a guess. Understanding what all the connections involved actually are would be a big help for me.

Thanks everyone.