P0420 and smog FAIL :(

[chewie_jrc]

Hi everyone. I have a 2004 with 46K on it and have been throwing a check engine light. I went to smog my car (need to update registration) and failed the ASM emission test and found that the CEL was P0420 (Cat efficiency below threshold [Bank 1]). I failed the hydrocarbon and NO tests more specifically. The results are as follows:

15 MPH HC in PPM: measured=96 (max=96)
25 MPH HC in PPM: measured=43 (max=57)
15 MPH NO in PPM: measured=971 (max=451) OUCH!
25 MPH NO in PPM: measured=677 (max=746)

The car has a CAI installed and according to the previous owner, there is an aftermarket header installed. An interesting thing to note is that the CEL will turn off by itself when I drive home to visit my parents in the high-desert (high elevation whereas I live at sea-level).

The CEL used to come on intermittently when I first bought it from the previous owner a few months ago. It now stays on 100% of the time. Could it be the rear sensor going out, or is it more likely that the CAT is going out (or perhaps the guy jacked something up when putting in the header)?

Thanks!

[RedSiBaron]

Hi everyone. I have a 2004 with 46K on it and have been throwing a check engine light. I went to smog my car (need to update registration) and failed the ASM emission test and found that the CEL was P0420 (Cat efficiency below threshold [Bank 1]). I failed the hydrocarbon and NO tests more specifically. The results are as follows:

15 MPH HC in PPM: measured=96 (max=96)
25 MPH HC in PPM: measured=43 (max=57)
15 MPH NO in PPM: measured=971 (max=451) OUCH!
25 MPH NO in PPM: measured=677 (max=746)

The car has a CAI installed and according to the previous owner, there is an aftermarket header installed. An interesting thing to note is that the CEL will turn off by itself when I drive home to visit my parents in the high-desert (high elevation whereas I live at sea-level).

The CEL used to come on intermittently when I first bought it from the previous owner a few months ago. It now stays on 100% of the time. Could it be the rear sensor going out, or is it more likely that the CAT is going out (or perhaps the guy jacked something up when putting in the header)?

Thanks!

are you sure it has a cat??? could it just have a raceheader??? or have a test pipe??? get under there, take some pics...the cat wont be going out, no way...and an o2 sensor SHOULDNT be bad yet...

im not trying to be mean or nothing, but this is why id ont buy modded cars...its just upsetting when shit happens and you knows its cuz someone screwed with something but you dont know what work has even been done...

[chewie_jrc]

I'm sorry, I forgot to mention that yes it DOES in fact have a cat. I will get under and take some pics later once my friend gets home (he has my jack and jack-stands).

[Kodeen]

I'm sorry, I forgot to mention that yes it DOES in fact have a cat. I will get under and take some pics later once my friend gets home (he has my jack and jack-stands).

Do you know if it is the stock one or an aftermarket, possibly high flow cat?

[!@#$%]

This same thing has been happening to me at 93k miles. I changed to a newer stock cat and all seems well.

[chewie_jrc]

Hmmm, I am not sure if it is a stock cat or not. If it isn't, where is a good place to get a stock cat (at least just for the smog test).

P.S. Would aftermarket headers be enough to fail emissions with the stock cat in place?

[05silversi]

Where is a good place to get a stock cat (at least just for the smog test).
On here in the classifieds, post a WTB.


Would aftermarket headers be enough to fail emissions with the stock cat in place?
No.

[chewie_jrc]

Yeah, on closer inspection its an aftermarket cat after DC shortys. I guess I'll just swap out the high-flow for a stock cat.

Does anybody know the legalities of changing cats in california (ie, do I need to have it done somewhere)? Guess its not a huge deal, since the guy passed of my cat during the last visual inspection but just for my own curiosities sake.

Thanks.

[talonXracer]

Are you sure it isnt the test pipe that appears to have a cat, but doesnt? Not sure who makes it.

[AUTiger]

megan used to make a resonated test pipe

[chewie_jrc]

Are you sure it isnt the test pipe that appears to have a cat, but doesnt? Not sure who makes it.
Nevertheless, its causing me to fail emissions (damn california). Is there a reputable aftermarket OEM-style cat that anyone would recommend? It's like $1000 going through the dealer....yeah right. I would post in the classifieds here but apparently I need 50 posts.

Thanks again.

[bdooley]

maybe it needs the defouler mod

[chewie_jrc]

The defouler mod will more than likely rid me of the CEL. It will not, however, makeup for the twice the legal hydrocarbon emissions. I think my most likely course of action is to get a cheap stock cat, swap it out, goto the smog guy and pass smog, then swap back for the high flow cat and implement the defouler mod.

[02nhbpep3]

yes the sim will remove the code, I had the same code for a couple months and threw on my advance "custom" sim and I've driven 200 miles and no cel. Not sure what I was blowin on the sniffer though they don't use them at all shops around here.

[Bificus]

http://www.ephatch.com/forum/showthread.php?t=46477
Have a look here.

[talonXracer]

I have had a aftermarket cat on my set-up from the beginning. This is what I have used, a JRrh and a Car-Sound universal cat.
http://i54.photobucket.com/albums/g96/talonxracer/IMG_0340.jpg

And a SSR header with a Car-Sound spun Platinum cat.
http://i54.photobucket.com/albums/g96/talonxracer/ssrandcat-1.jpg

[serialdriller]

Just curious, is the base RSX cat the same as the ep3 cat? thanks