I was checking the air filter on my Son's Xterra when I noticed a hose that looked like it should have something attached to it. It has "TN5XO" written on it. The reason I think it had something attached, or was plugged into something is because the end looks cleaner than the rest of the hose. I've never noticed it before. The hose looks as if it goes under engine to the Oil Pan or Transmission. I couldn't tell.
Any ideas would be appreciated.