2003 Catalytic Converter Replacement (P0420) / C.A.R.B.?

[PathyPop]

My son's recently purchased 2003 Pathfinder with 120k miles has a CEL with code 0420. There's ton's of information posted about this code and it likely meaning a cat replacement but we're in California with stricter emission laws. This PF is originally from Pennsylvania but moved to California when it was two years old. Does anyone know if the cat should be replaced with a CARB cat, or should it be a "49 State" OEM version like it has. At RockAuto the CARB compliant version is ~$250 and the non is ~$175. The CARB version has a noticeably longer catalyst chamber by 3-4 inches and I'm not sure about the rest of it, or if it will bolt right up. It also has a full surround heat shield that the others don't seem to have.

Also, for anyone who knows about this: I plan to try the oxy plug extension to see if that will turn off the CEL until I get around to it.

[atraudes]

The long and the short of it is you should replace it with whatever it was originally equipped with, especially since it sounds like the alternative won't fit properly. It being from Pennsylvania you'll likely want the non-CARB cats. However, you should be able to objectively confirm whether it's a CARB vehicle or not based on stickers that will indicate one way or the other. Per this article,

You can identify a CA or Federal vehicle by the emissions system label. Try looking in the door jamb, on the front radiator support, strut tower plate, or under the engine hood. The label will say something along the lines of "This vehicle conforms to...regulations applicable to...". If "This vehicle conforms to..." mentions California, the vehicle was manufactured to CARB standards and you'll need to purchase the CARB/California parts. If "This vehicle conforms to..." does not mention California, the vehicle was manufactured to Federal EPA standards and you'll want to purchase the Federal/Non-CARB/Non-California parts.

FWIW, I replaced both of mine with Walkers when I first bought it 4 years ago and they're still going strong.

Be warned though, catalytic converters don't go bad on their own. Given a properly running engine, they should easily outlast the car. Make sure you've identified the cause of their failure or you'll end up doing it again in another few years (maybe sooner). The fact you're only getting P0420 and not P0430 indicates you've got a problem on only one bank. My offhand guess would be a leaky injector. You can pull them out and get them cleaned/inspected for about $100 which is a worthwhile endeavor anyway, given their age. In my case the fuel pressure regulator was leaking a bunch of fuel into the intake manifold which was causing problems for both sides.

Hope that helps!

[PathyPop]

Hope that helps!

Thanks for the article, very helpful. I cleared the code and it hasn't come back (yet). I think it was because a week ago I pulled the rubber intake to run a android scope to check the power valve screws and I used some carb cleaner on the butterfly valve. I didn't get the CEL at that time, but my son did and didn't tell me until later. Reading about how carb cleaner can be trouble so won't do that again.

For the sticker, it states it conforms to NLEV California regulations so maybe they are all 50 state, but doesn't explain why CARB and non-CARB cats are offered. Hope I don't need to find out tho.

[atraudes]

NLEV California? Well that's a new one to me, though I'm leaning towards CARB. Give the manufacturer of the cat a call before you buy and see if they can give you some reassurances.

Fingers crossed it's a moot point!

[PathyPop]

Fingers crossed it's a moot point!

Yup on this ^

the sticker is the same as this one (midway down):
http://www.autorepairinstructions.com/a ... -manifold/

[fueler]

Be warned though, catalytic converters don't go bad on their own.

Yes they do, I have seen several go bad. I currently have three cars with bad cats myself!

[850pathfinder]

I just rebuilt my 03 pathfinder w 160k miles. both cats had ice cream scoop chunks missing out of both cats due to the upstream o2 sensor's cage, that goes around the element, coming apart and grinding away. The old downstream o2 seonsors were exactly the same condition but the metal cage went farther down into the exhaust and didnt cause any muffler damage. What im getting at is to make sure you replace all the o2 sensors. The Old downstreams were so shot they didnt recognize the bad cats but didnt fail the warmup or voltage lag checks. After i replaced the o2 sensors i had p0420 and p0430. Replaced with walkers and no problems for the past month. make sure you get the catalytic converter gaskets. FEL-PRO 61339 or the OEM 20840-7J610

[atraudes]

So I noticed my catalytic converter sticker today while doing some other things and thought I'd post it in case it's helpful. I used non-CARB cats and had no problems.

[PathyPop]

Yes, that's the same sticker I have. Not sure why Rock Auto shows 50 state and CA only versions, but I hope they will ship the "50 state" version to CA if I need it. So far so good though. My CEL is staying off and the scanner is showing good readings from the O2 sensors.

[x2002Qx4x]

Not sure if there was a solution to this problem, but I have had P0420 for over 100,000 miles (now have 220,000). Replaced oxygen sensors around 150,000 miles and cat shows fine on the scanner graph still. Part of the problem could be that Nissan issued an ECU update about 6 years ago that fixed why this code was showing up on so many vehicles. When I clear the CEL for another code, the P0420 will sometimes come back on and will stay off until I reset it again. Maybe try taking it to Nissan and having them update ECU if they'll be nice and do that for you

[vizjournalist]

Hi Folks.

I'm about to attempt a replacement on my passenger side TWC as well. Same vehicle: 2003 qx4 with just under 200k

So to clarify... if the emissions label mentions California at all, the vehicle requires a CARB cat? I sincerely appreciate all the help you can provide. I just want to be sure I'm required to spend the extra money before doing so.


My Tag:

[sigman70]

My understanding is this: if the emissions label says California AND if your car is registered in California or New York, then yes you must have a CARB cat...otherwise no you don't. My emissions label says California on it just like yours and I just replaced all 4 of my cats on my 2002 and went with the Magnaflow ones...they are not CARB compliant as my car is registered in Ohio. Hope this helps!

-Dave

[Blindaviator]

Back at the beginning of the year when I was in California and looking to purchase a vehicle I happened to look up Cat's as several of the vehicles I found all said they needed some types of emissions work.

What I found as I looked around is that all the places that sell new cat's online are prevented, I'm assuming by California law, from shipping ANY non CARB compliant emission part to a california address. As I investigated further, and talked with some friends, most of them told me what they do is go to a salvage yard (or find someone parting one out) and pull a used cat off another vehicle similar to theirs (preferable same make / model) and slap it on the vehicle to get it inspected. I don't know if this is legal to do since it is an emission part but they have had no issues with it.

[fueler]

My understanding is this: if the emissions label says California AND if your car is registered in California or New York, then yes you must have a CARB cat...otherwise no you don't. My emissions label says California on it just like yours and I just replaced all 4 of my cats on my 2002 and went with the Magnaflow ones...they are not CARB compliant as my car is registered in Ohio. Hope this helps!

-Dave

I believe that is true, but it's not normally enforced here in CA. People get aftermarket cats all the time, and never causes an issue during smog inspections. Funny how most exhaust shops will sell & install aftermarket cats, but the Nissan dealer will tell you that's illegal and your only option is a $2500 Nissan cat.

[carnal_c30]

Resellers are prohibited from shipping non CARB cats to California. Regardless of where the vehicle was originally sold. Every catalytic sold or shipped to California has to be a CARB cat whether for a 1978 Ford or a 2013 Nissan.

No online seller wants to get caught selling them so that's why Rock won't ship. I work in the industry and we even are scared to ship samples that aren't CARB approved. Sometimes your local muffler shop may have access to cheaper ones, but its getting more difficult.

Try to stick to a quality name, none of them are as good as OEM but some are so bad you'll still get the P0420 even with the new cat (ofcourse there are valid reasons this could happen with the replacement using a OE or quality cat so make sure you do what you can to diagnose properly)

[PathyPop]

As I investigated further, and talked with some friends, most of them told me what they do is go to a salvage yard (or find someone parting one out) and pull a used cat off another vehicle similar to theirs (preferable same make / model) and slap it on the vehicle to get it inspected. I don't know if this is legal to do since it is an emission part but they have had no issues with it.

In California it is illegal to sell a used cat. They aren't listed as available parts at the salvage yards and they are removed at the self-pick yards. The reason, at least in part, was because of theft. They are so expensive and often easy to get to, that they were being cut out, even from new car lots. There are some available on CL though, if one was to get lucky enough to find the one they needed. For Rock Auto I can put a non-CARB cat in my cart under my California account and it doesn't warn me I can't order it, but maybe it will if I actually place the order.

For me, so far, no more P0420 code.

[fueler]

In California it is illegal to sell a used cat. They aren't listed as available parts at the salvage yards and they are removed at the self-pick yards.

This is also something I have always heard here in CA, but isn't enforced. I have bought about 10 used cats from junkyards, most of which were for people who thought they were impossible to get. My junkyards install cats for $75 extra

[vizjournalist]

I appreciate this thread and the advise. I'm going to move forward with the non-carb variant.

Question: There are several versions with and without heat shields. Is purchasing a version without a heat shield a reasonable choice? It appears that some have heat shield mounting points, some come with the heat shield and others have no way to attach the shield. What would you recommend?

[fueler]

I go without heatshield, they just end up breaking loose and making noise.

[vizjournalist]

Awesome! That will save me a few bucks. If I can manage to do the install on the passenger side cat myself (50/50 chance) I'll make a post. I suspect I'll need a torch and tap / die kit as it has never been replaced...

[atraudes]

I'm guessing the ones without heat shield intend for you to transfer the old shields over. I remember the shields on my original cats were bolted on, whereas the new ones were welded in place.