OBD II Codes P0420/P0430, 2003 Highlander 2.4L

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Great info, gentlemen. The non-foulers are going to be my fallback position if the CEL comes on again, for sure. They don't look that hard at this sort of thing around here and I wouldn't even feel guilty because the car will still (most likely) not be polluting more than spec.

Also, regarding the earlier idea about the cat being two chambered due to being a California car, I did a little research. the listing that shows the two different manifold/cat assemblies indicates a date range of manufacture. It is possible that the two chambered cat was used as a way to give the engine a little more low end torque. My girlfriend believes that her dealer friend got the car from an original owner in Louisiana.

I think we've about beat this one to death at this point and I really appreciate the info!
 
The decal under the hood should say if it has CA or Fed emissions. If you have scanner, look at the Mode 6 data. If I am not mistaken, catalytic converter test results are generally the are the first few TIDs. You can verify that all the I/M tests are completed and there are no pending tests and you can see if you have reasonable margins on the completed test.

I am shocked that NJ inspection is looking for the O2 sensor extension. Don't they just hook up to the OBD port like all other states and print the emission sticker? The car is not even on the lift when the emissions are tested in the states that I am familiar with.
 
My device is just a code reader. I need to get myself a scan tool. The ones that connect to a computer are pretty cheap. Before I moved to Texas in 1976 I lived in New Jersey. When Texas tried to implement a centrally controlled state inspection program in 1995 (aborted) it was modeled after NJ's. But, when I watch them inspect on an OBDII car here they do just plug it in.
 
I ordered a scanner. Since I am now in the OBDII arena I need something better than just a code reader. (My 1989 Accord had an ECM, but it was pre-OBDI) If the CEL lit you counted flashes on an LED that was on the ECM to identify the troubled system. Pretty spiffy for 1989, but like flint arrowheads compared to now.
 
I bought this scanner at tmart.com, but they are all over the place for about $50. It is basically a superseded model from the maker. It is not too bad, though, it does not get along as well with my Mazda as it does with my girlfriend's Highlander. I was able to read both banks' O2 sensor voltages. The post sensors read an almost constant 0.7 volts while the engine was running - both sensors. The voltages were very steady and did not fluctuate much with changing RPM's. So, based upon the video above, it appears that her converter is working just fine. Perhaps the CEL was a fluke due to a short in-town trip she made when the temp was below freezing. It has not come back on since I reset it over two weeks ago. Thanks for all the help, guys!
 
see, now you can make intelligent decisions rather than throwing parts randomly at a problem :) MS509 is a nice unit; I paid over $100 on sale when it was fist available as a Centec model from HF but my second one was under $50 from Amazon when my MS300 found not to extract code from the 2000 Maxima.

Only thing which I wish MS509 had done differently was to have a real working on/off button. This turns itself on as soon as you connect and thus can not be left connected to the car like I used to do with my older scanner.

By the way, you should check the I/M status to make sure all the tests are being shown as completed. If the cat converter is showing as incomplete, you are not yet off the woods.
 
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I was simply watching the live O2 sensor data as shown in the video. I did the temperature test and the O2 sensor test. To my thinking I am satisfied that the cat is OK. Time will tell, I suppose. I still have the non-fouler option if needed, but I would not do so if the temperature test indicated a restricted cat. At that point, she would have a decision to make about an major expenditure.
 
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