Rear Catalytic Converter

[AutisMDXTypeS]

Originally Posted by DelSolMarine

my point exactly to the early debate in this thread... can the 3rd cat just be killed, at failure, to stay in emissions compliancy?

From what I know,( disclaimer...not much) but you can't KILL a cat cheaply, you can only fool a cat. I've heard of racers drilling a second hole in places to stick it in the cat ahead of it or later inline...never made sense to me. I believe in (really) doing what you have to do and keeping it clean. I've heard guy doing bypass flaps on the street in California to open her up to race and closing it if a cop pulls them over( they have mobile "sniffer" trucks out there I heard) or guys on the East coast here swapping exhaust for inspection. Sounds like to much work.
LS short, if you kill the cat it might not pass the sniffer, then what ya got?
"Same verse as the first"
Back to the lab again!

[OneTonSoup]

No sensor is there for the 3rd cat, only the 4 sensors on the 2 primary cats.
My '04 is labeled a ULEV... Ultra Low Emissions Vehicle. I'm guessing the 3rd cat on the '03 - '06 MDX is only to bring down the emissions enough to get that label. With just the two primary cats, I think it'd still meet the regular emissions level requirements. I haven't measured anything, just guessing...
I'm going to be replacing my cat/mid-pipe/first-muffler with larger pipe & a magnaflow 1in2out (3"in-2.5"out) muffler and adapt it down to the rear muffler pipes. Seems to me that the cat & midpipe are the greatest choke points in the exhaust.

[TavuL]

I don't know what's the issue for emissions and all that...a hair spray breaks more the ozone than CO2 emmissions from cars lol ( I am beong sarcastic, not well informed on that matter nor any research done lol) anyways here's the reason for the 3 cats ULEV! that's why they don't want low emmissions they want ULTRA LOW EMMISSIONS just as always acura giving the extra mile....2 cats will pass anyway....but we can say our luxury SUV exhale CLEANER gas lol

[mdxer12345]

So, for someone with 0420 code on 2003 mdx? it's most likely cat convertor replacement? anyone know how much the part was and cost at dealership? i don't think going non oem on a cat convertor would be reliable.

[icebergtec]

So the check engine on my '07 came on around 96k. The dealer changed on under warranty. The light went off. However, a week less than a week later, the light came back on. When I took it to the dealer, they told me that the Oxygen (O2) sensor is bad and I need to replace it. Is this typical/common/usual? They want around $370 to change O sensor. What is the opinion form the experience folks here?

Thank you.