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Old 12-12-2012, 10:40 AM   #1251
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Join Date: Apr 2010
Location: Toronto
Posts: 6,940
My Ride: 2004 M3, 2001 325i
Originally Posted by lrz14 View Post
Yea i just been hearing a lot of different stuff like others saying that the post o2 sensors dont really and ignore them to loosing performance on the car not having them on so i have no idea what to believe. Any idea what the pre cat sensors do?
Everything. Air/fuel mixture.

Your car won't run without them.
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