04 Jetta needs a cat....

[dad911]

throwin codes, can't pass NJ inspection. Is this a diy?

Can it be aftermarket? Since we left the Paris Agreement, can I just empty out the old one? Or will it still throw codes?

[Bob Kontak]

You can't empty.

What you can do is give us the codes.

P0420 is the usual suspect.

Upstream leaks at flanges before rear O2 sensor will throw this code if cat is good.

You can buy a down pipe with cat for 203 on r o c k a u t o but I am guessing on engine.

Yes it's a DIY job.

[asphaltgambler]

It is DIY but it needs to be OEM if you want it to last more than 6- 12 months with an aftermarket unit.

[dad911]

Bob - p0420

[Bob Kontak]

Originally Posted by dad911

Bob - p0420

Bet you have a leak downstream of the main cat and before the rear O2 sensor. It confuses the rear O2 sensor because it sniffs false oxygen.

For $120 you can have a small muffler shop weld a sleeve in to snuff the leak, if present. Those guys can do wonders. Even Midas.

I cannot argue with asphaltgambler. You pays your money and you takes your chances.

To expand on P0420, it has to do with the reading from the rear sensor. The front sensor does the real work. It sniffs the raw exhaust and tells the computer if it's rich or lean. The computer adjusts the fuel to offset. When the exhaust exits the primary cat it is sniffed again to see that it's nice and steady with a constant tail pipe ready O2 content. If the readings are outside expected, the code is presented. Air leaks or a cat that is not doing it's job. Maybe a faulty O2 sensor but I would nix that thought initially.

[john70t]

If they ship it to all 50 states it's Cali ARB certified and probably of decent enough quality to use on a 13yo car. RA is decent afaik.

If the cat is clogging(and not a leak as mentioned) there may be oil control or an ignition/bad plug or fuel/leaking injector malfunction that will destroy every following cat you throw at it.

Drive it around and then check the pipe temps before and after with an infrared thermometer.
Should be 50-100 more after which indicates HCs are getting burned up and it's functioning.

[John Rogers]

You will have to check to see if the state you live in requires the smog equipment must be purchased from the dealer and be dealer installed? This is the law in CA and the total cost for a cat for my 2007 Chevy HHR would have been about $1200 and the dealer does not have them in stock! I checked with several muffler shops, even one close to the Mexico border and they said they can not even sell me one! BUT the guy at the last place told me the ones the dealer sells are exactly the same as the best one sold by ********.com! Of course they will not sell me one either......but I have two daughters who live in Phoenix, no smog issues so they ordered one then sent it on to me. The factory one has a tag on the top - rear that is not visible and the new ones works exactly the same as the dealer one, $168 vs $1200 and no smog issues.

[dafischer]

John
Thankfully NJ isn't that draconian in it's inspection and emissions program.

[Arizona_928]

To think I removed the cat on my alh