|
The front sensor, pre-cat, is what your car uses to "fine tune the mixture". You don't want to mess with that.
The second sensor (after the cat. converter) allows the car to measure the efficiency of the catalytic converter since it now has data on exhaust gases both pre and post cat. That is all.
I'm not familiar with the spacer but I presume that the idea is that by pulling it out of the stream you trick it into a more favorable reading; it believes that the cat. is still doing its job, et voila!, no CEL. Bear in mind that if your state inspector is strict they may cry foul if they find that spacer.
Best,
Will
--
XC60 / Odyssey
|