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      03-28-2012, 07:47 AM   #5
JimD
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Drives: 128i convertible
Join Date: Apr 2009
Location: Lexington, SC

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With respect to codes, it depends on where the O2 sensors are. I have not researched my bimmer so I only know generalities. Modern engines have two O2 sensors that are before and after the catalytic converters. They both are looking to see if the air to fuel ratio is correct but the one after the catalytics also judges the converter's condition. If there is a O2 sensor bung behind the catalytic you remove and you thus remove the O2 sensor, that will throw a code. Even if you add the O2 sensor back, I would expect some codes because your exhaust without the converter will not look the same as it would with the converter. If the O2 sensors are all upstream of what you remove, there should be no codes.

Jim
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128i Convertible, MT, Alpine White, Black Top, Taupe Leatherette, Walnut, Sport
Ordered 5/22/09, Completed 6/4/09, At Port 6/9/09, On the Georgia Highway 6/13/09, Ship Arrived Charleston 6/24/09 at 10pm, PCD 7/21/09
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