Originally Posted by mrcoyote

My car is in the shop and they gave me an '07 C230 sedan to drive with 6K miles on it. As SOON as I left the dealership,
that car had a brutal squeaking noise kinda like a repetitive chirping coming from what seemed like the center of the dash.
VERY irritating to say the least. I would have taken it back immediately for another car it was so bad, but I was already out
on the freeway, and I thought of something I had read here on this forum about this problem MB has had with these cars and
this particular squeak. I remembered that it was something NOT inside the car, but under the hood in the rear by the firewall.
So, I took the car home, popped the hood, and looked in back of the engine up against the firewall.....and found what I had
remembered was the problem. Look for a braided nylon sheath with wires in it maybe 1/2 inch wide. It's held to the firewall
by what looks like some kind of fancy plastic clip thingy. Love that word "thingy". I pulled the sheath OUT of the clip and sort
of pulled outward on the plastic clip (away from the firewall). Looking at it, I thought........there's NO WAY that piece of plastic
and a nylon wiring harness could be making a loud chirping noise inside the car. No way. I would have bet on it. And, once again,
I would have lost that bet. Took the car for a test ride and GONE. Somebody posted about this, so I apologize and not trying
to rip off anybody's post, but.....I wouldn't have believed it myself if I hadn't heard it. It really sounds like it's right there
inside the car.

Maybe by posting this (again) now, it will save somebody a lot of grief tracking this thing down.
The cure might be to take a nylon wire tie or something and re-do it and then test drive it.
I'm not sure how many model years this problem is applicable to, but.......

mrcoyote[8D]