Vented vs Non-Vented
 

Got the CEL on my 03 and the readout was emissions evap. Gas cap looked like the rubber ring was showing its age. I replaced it with one from autozone, and noticed that when I unscrew, it makes a hissing sound, like its sucking for air. A few days went by, and it threw the same CEL. Do I need a vented gas cap?:confused:

Get a Porsche gas cap They are around $20

Seconded. I had a replacement cap on my car when I bought it. The Porsche cap from pelican was 14 bucks with a new strap. No Brainer.