E46Fanatics - View Single Post - Dealing with Headers, Cats, O2 sensors, and Emissions
View Single Post
Old 01-18-2013, 10:34 AM   #15
Banned User
Join Date: Apr 2008
Location: Dallas, TX
Posts: 2,217
My Ride: E30-E46-E90-E90M-F30
I have headers and aftermsrket cats and pass emission every year. No cat efficiency errors.

For ms43 and higher, the post cats do affect fuel trim. Ms42 is only for emission. Ms43 makes minor adjustments to fuel trim for post cats (keyword minor)

sent from my HTC EVO+ using Bimmer App

Last edited by flashmeow; 01-18-2013 at 10:35 AM.
flashmeow is offline   Reply With Quote