You're referring to the vapor canister. I replaced mine a few months ago because the insides had somehow fallen out within the last year. The motor doesn't need it to run, but I like to have my emissions stuff working, what's left of it anyway, better for the environment. It's in the engine compartment underneath the master cyliner. The only reason I'm asking about this thing under my left taillight is because I'm going to be doing some work on my taillights soon and it will have to come out. And if it's not important, I'm just not going to put it back in. I'm just curious exactly what it is.