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      07-26-2021, 12:33 PM   #3
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Originally Posted by chhappy7 View Post
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.
It will pass. It does what you said "prevent the monitor from throwing a code". This is not to be confused with setting the monitor to "pass". That would be illegal.

If your state allows monitor(s) to be in the "Not Ready" but not "failed" state, then you can pass as long as your "not ready" count is below that state threshold.

For eg. Many NE states like NY and MA allow 1 monitor in the "not ready" state. If the cat is the only monitor in this state you will pass. This is assuming that they don't attach anything to the muffler and do a sniff test, or have grounds to do a visual inspection under the hood.
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