Update!!! I looked at several other forums and found recommendations to simply replace my gas cap and disconnect the battery.

SUCCESS!!!

I did that on Monday and no CE light. Gas cap cost about $12 at the local autoparts store. The members the other forums stated the expected life of the gas cap is 5-7. My 4rnr is a 2004.

DTC P0430 CATALYST SYSTEM EFFICIENCY BELOW THRESHOLD (BANK 2)

I don't think replacing the gas cap is going to fix this code. Reason being, it will be a completely different code altogether (like a P0455 or P0456--Evap. emission control leak detected).

This code is getting set off because the PCM doesn't like what it's seeing from the oxygen sensors(which are the rear ones, the front ones are air/fuel sensors, just to detect lean/rich running conditions). So that means either the O2 sensor is bum, or the converters aren't doing their job.

My suggestion is if you don't have an actual scanner, to either replace the bank 2 rear O2 sensor and try it, or pay any reputable shop to scan it for you, so you can do the work at home.

My 06 had the same light on, but it was under 80k miles, so it was Federally Mandated Emission Warranty. I got three new catalytic converters out of it

I already replaced the bank 2 rear sensor. So I will wait and see how this works. If it does not work then I will get a shop to scan it and do like you said do the work at home.

Thanks.

Like my wife says "Once again I am wrong" lol

I left the office for lunch 30 mins after my last post above this one and the CE light came back on. I am thinking I am going to have to replace the catalytic converter on bank 2.

Thought any one?

As was stated before, you gas cap will not cause a P0430, it is a completely different monitor than your Catalyst Efficiency. I posted some helpful information in an older thread regarding catalytic converters and diagnosing codes such as these. Instead of taking the time to rewrite the post I am just going to go ahead and pull it for you and post it here.

~

Most if not all car manufacturers use the same testing parameters for catalytic converter efficiency, they will use a Pre-Cat O2 or AFR Sensor and a Post-Cat O2 sensor to measure the effective "oxygen storage" and from that it gives its result on what it thinks the catalytic converter's health is. That's it plain and simple, the ECU will look at Pre-Cat O2 levels and then Post-Cat O2 levels to determine if the catalytic converter is actually working. This presents a small plethora of possible problems and scenarios ranging from complete catalytic converter failure to biased O2 Sensors. The reality is that this is nothing more than a Go, No Go test, because the catalytic converter does not deal only in O2. The only proper and 100% accurate way to test a catalytic converter's efficiency is to preform an intrusive test, where you drill into the cat and use a 4 or 5 gas analyzer to verify functionality. But, most people don't want to drill into the cat and most customers don't like that idea either...

In any case, if one of these codes is tripped you should always assume an "innocent until proven guilty" frame of mind towards the problem. First test the O2 sensors individually and then compare to what the scantool is providing as information. After verifying that the sensors are working properly and that the scantool data is in-line with the sensors I would hook up a 4 or 5 gas analyzer to the exhaust and measure the gases. This won't give you a 100% accurate view of what is going on, but it will help you figure out what the catalytic converter is doing. Without going deeply into the operation and chemical reactions that occur inside of the catalytic converter, the gases will vary according to what is actually happening. For example, if your catalytic converter was working well there would be little Oxygen coming out the tailpipe because it is used in reaction to modify quantities of NOx, CO, CO2, and HC. Keep in mind also that the catalytic converter is NOT the problem, a catalytic converter should last the life of the vehicle or at the very least a whole hell of a lot longer than most people will keep the vehicle. If the vehicle is operating as it is supposed to your catalytic converter should not fail prematurely, this is a SYMPTOM of another problem, not a problem in it self. Something to keep in mind when dealing with these codes/repairs, because I have seen guys slap a set of sensors and cats on a car and have it come back with the same problem months down the line because the real problem trashed the cats again.

There are other things to consider, such as if the vehicle has been driven with faulty sensors for a long time sustained damage to the catalytic converter may have occurred and it will need to be replaced anyways. The sensors may have damaged the cat but it could be "brought back to life." I have seen catalytic converters be brought back to life before, but really its a 50/50 shot in the dark.

Here are some links:
HowStuffWorks "How Catalytic Converters Work"
http://www.converterwarehouse.com/te...rter-&News=100
Catalytic Converter Tech Tips : Catalytic Converter Replacement : ConverterWarehouse.com
All Catalytic Converters - How do I know if my catalytic converter is defective?

Hopeful this will help you out.

A great write up...

All I can add is that there are some cars and manufactures with known and common Cat problems... is you get this code in any GM from 2001-2003.. You can save all of these tests... You can bet your left one that you have a bad Cat... Very common (with TSB's to back it up).

One DIY test that you can do with a 0430 code is a WOT run at highway speeds... If this generates a misfire or lousy performance, then you know you have a bad Cat.

first off i have 2 questions haha
1. what is a WOT run at highway speeds?
2. would i be able to take my manifold off and put a universal cat on it?

Sorry about that... I thought that most every car guy would know what a WOT run is...

WOT = Wide Open Throttle... Get the truck up to 55 MPH and then bury the hammer. You will know long before you get to 75MPH if it is misfiring. If you aren't sure try this going up a hill. If you're not sure, its not misfiring...

lol ok now i feel stupid, oh well im in my last week of college and its killing my brain..thanks for clarifying, hopefully someone can answer my second question!

I am having the same issue in my 03 V8 with 193K. I replaced the front sensor on the drivers side about 6 mos ago. CK Engine light left for a while. Comes off and on intermentiently. I am hoping its not a cat since I have not lost fuel mileage or performance. Any and all suggestions are welcome.

I had the same problem and replaced all 4 O2 sensors then 2 months later I got a CE and replaced the one bad sensor and now it is good. Those sensors are made cheap so they can be bad even when new.
I am going to send my 2 month old one back to Denso to try and get it replaced.

I had installed the urd y-pipe on mine & about 90 mi. n threw 0420 so checked all the old posts on here & 120 ,bought both r sensors on amazon . Just as a lark also bought new gas cap as it is sorta one of the 1st things THEY say to check (probably f ing myself here) cleared with obd 2 & no cel for 2 tanks of gas ! Some really good old posts if search under "sensor" helps explain alot some is previous Blackworksinc & others with more knowledge than me !

If it comes down to it, you could always get some high-flow cats

Must be 50 st legal n Kali ! Most after-markets don't have correct material n them ,unless you re-install all 4 of them

I'm sure you can find some.