What is this metal line near the Oil Dipstick (M54)?
 

I was checking the oil level on my car and was curious what this metal line is? I noticed that the black plastic piece is very loose between the hose and the metal line.

Is the black piece just some kind of cap? The hose seems to still be secure to the hard line, but I can move the black plastic piece (circled in red) easily.

I'm about to head out on a trip and hope this isn't sign of something about to break! :wow:

https://imgur.com/a/LeOdgjc

https://i.imgur.com/RR91tLk.jpeg

That is a fuel line to the fuel rail/injectors. The black plastic is to disconnect the fuel rail to the fuel line

^Indeed, and its normal on that type of quick connect fitting for the black plastic to be loose like that.