Hi all,
Just doing some routine checkups after doing an oil change.
Took the top of the air box off to see the condition of the air filter and then I notice another filter fixed to the inside top of the air box. Its gray in color and ribbed. Didnt fall out and I also didnt want to pry it out not knowing if its a permanent filter or what? I searched around and no word of what it is. Sites dont have it listed as an air filter so im guessing it might not be removable. Dont know. Ideas?

this was on a '03 325ci BTW.

Im pretty sure that is a carbon filter it is there so that gases from the engine do not escape when the engine is off.

I have seen cars that use a small filter in the air box for the pcv system. the free 92 ford f150 my friend got has one it is a very good thing, because it keeps sludge from colecting in the intake and tb after a while. some cars just have a tube that conects to the intake.
it takes oily vapors from the crank case caused by cylinder ring blow by, wich if not evacuated will build up pressure and cause seals to leak. ect, and routes them back to the intake so the engine can burn it and there is no bad emisions.

It sounds like the air filter from an M56 SULEV engine, but I thought it was only available in the sedan. Is your oil filler cap hinged?

Pics?

The airfilter on my 03 325 has two parts...a paper filter and a grey foam piece...it all comes out at one unit and both are replaced together.