Hi, had check engine light, code P1504. I found that a plastic accordion hose from the passenger side valve cover to the plastic throttle body housing had broken. Also, it was filled with this strange brownish-white sludge. I replaced that hose with a rubber hose, and cleaned up the throttle body, and removed and cleaned the Idle Control Valve as well. I noticed another one of those plastic hoses that exits the plastic throttle body and heads the other direction towards the driver side somewhere, but I can't easily see where it goes.
a) where does this one go?
b) is it likely to be sludged up also and need to be cleaned?

I am reluctant to touch it, since the original broken one just kept breaking into more and more pieces the more I messed with it, including having the squeeze rings break off at both ends. This plastic material is junk after 14 yrs, and I am assuming I will get 'hosed' (sorry) at the dealer to get new OEM ones.

 

Those hoses go to the back of each valve cover to the air intake. They are about $135 each.

 

Yup, those are the PCV breather hoses. They suck. Replace them for sure. What size ID hose did you use? I've been wanting to do this.

 

I got the main hose off eBay for $60.

 

I would replace both for that price.
As far as the crud , they all pretty much have that. especially in colder climates. Some BMW's have insulation on the breather hoses to prevent that crud from forming.

 

I replaced the passenger side with a 1 inch heater hose for now, not sure if the larger diameter matters.. I might spend $60 for the correct one, but not $135....