DrGP

If you look at the schematic, I found no part #7. Perhaps it was not included in early models or a Tech removed it?. Otherwise, everything was clean . I guess if there is no pre-filter, there would be no debris trapped.<ul><li><a href="https://forums.audiworld.com/s4b6/msgs/383205.phtml">Schematic</a></li></ul>

bhvrdr

at the bottom as that is where all the debris has now gone. I found a cigarette butt in mine once if you can believe that. You can use the woman's nylons if you want a temporary solution.

daveak05

It can fall down inside the air box if not careful. Like bhvrdr says, check for it. And if missing, I would replace.

s4for5_TTfor2

Are you sure ? it should be tucked up INSIDE item # 6 , rear side

DrGP

There is nothing inside #6 except some wire clips

ruknd

same thing happened to me...I havent replaced it

s4for5_TTfor2

no big deal, if you decide to keep the car put in a new main air cleaner.

JeffreyL

I've never had any debris in my pre-filter (after two years), so I assume I don't need it. I've had it in for two years, but I could probably just remove it. If you typically drive in areas that don't have a lot of leaves and other debris in the air, then you probably don't need it. Obviously some need it because they've found all kinds of junk that the prefilter has caught. But even in that case, if they didn't have the pre-filter, then the main filter would have filtered out all of the junk. The prefilter is helpful in keeping all of that junk out of the area of the main air filter.

40valves

airbox waitin for ya.

S4PR

never had it in the first place. Mine is a late 10/2003 S4 and it never had the pre-filter. Just changed the air filter at 15K and the air filter box was pretty clean. By the way I live in sunny Puerto Rico so the weather conditions are definitely not the same. Hope this helps.