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      07-26-2021, 01:11 PM   #2
chhappy7's Avatar

Drives: 2015 328i RWD
Join Date: Mar 2018
Location: Hanover, NH

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2015 328i  [0.00]
Originally Posted by Sad N26 View Post
I am considering upgrading to a high-flow catted downpipe. However, we all know that even a catted downpipe will throw a code and cause the Check Engine Light to come on.

I understand that Bootmod3 can be programmed to eliminate the CEL. My question is: how exactly does it eliminate the CEL? Does the Bootmod3 programming allow for accurate reading of the exhaust through the O2 sensor but change the parameters within the DME as to what are acceptable readings in the exhaust? Or does it "trick" the DME into reading cleaner exhaust gasses? Or does it allow the O2 sensor to read accurately but it just overrides the DME's attempt to go into "limp" mode? or is it none of these?

Forgive my ignorance if none of these are legitimate possibilities.
I'd appreciate some clarification on how the CEL is eliminated. Thanks!
Iirc it just turns off the monitoring. So if you were to go do a emissions test with Bootmod3 cancelling the CEL, it will not pass.
2015 328i - M Sport front&rear bumper/diffuser, M3 style fender/side skirt, M Performance brakes, BBS SR, ceramic iDrive, LCI radio trim, 6WB, NBT EVO, X5M razor key
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