Oxygen Sensor Question

Previous thread: http://www.aveoforum.com/forum/f108/...26/#post179389

Cat was destroyed, replaced that with a 49-state cat (California car). P0420 came back, replaced both oxygen sensors (APWI upstream and NTK downstream). Now, I get P0133.

In the morning when it is cold, the car starts but idles rough for 5-20 seconds then is fine, no code. My wife drives it to work, no issues. However, the last two days (I cleared the code each day) when driving home in traffic, she says she will begin to accelerate and it it will be rough for a couple seconds, the CEL will come on, then fine.

At high RPM's/speed, it smells rich. It does not smell rich under normal driving conditions.

I thought, oh well, dumb me for buying the cheapest upstream sensor from some company I've never heard of. I was going to buy the NTK or the Denso, but I saw that on Rock Auto they have an AC Delco one that says "ENSOR,HTD OXY w/TIER 2 FED EMIS(NT7) or ULEV2 CALIFORNIA EMIS SYS(NU2) ".

Since it said California, I was wondering do I need that particular one since this car was manufactured for CA? It says ULEV2, but my car does not fall under that as far as I am aware. I have tried scouring the internet but I have come up with nothing.

Did you try Rockauto tech support? They must spend lots of time figuring this stuff out, and might have the answer you're looking for. But you would need to let them know you installed a non-CAL cat, because that might be playing into this as well.

I have not, no. I did not realize they offer tech support.

i would run the vin at the dealer, it seems you should be ca emissions, so you should verify that. Whether you put in a CA cat or not, the wrong o2 is most likely why the computer is throwing a code since you went with a non ca o2 sensor.

Dealer says on their end it says California specific... at a whopping $338... wow...

Found the same part number on Amazon for $85 shipped next day air so hopefully I will get it tomorrow.

The CA oxygen sensor should arrive here soon. In anticipation, I cleared the DTC's (it said P0133 and P0420) and disconnected the negative battery terminal so everything will be cleared when I install it. Also, with the bluetooth OBDII and the Torque phone app, I found this (I assume related to the incorrect oxygen sensor currently in there):

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Oxygen sensor came. I installed that and a new PCV valve for the heck of it. In the process of taking the old one out, it broke, so I took the valve cover off and got the old PCV valve out. That was Friday. Since, the car has maybe been driven for maybe 120 miles and the only code to come back is P0420. The car seems to start smoother, but that could just be my imagination. It definitely seems to run smoother, however.

Not sure what to do about the P0420 now, however. At this point I guess it's just because it's a 49-state cat in a CA CARB car. The only thing I want to confirm is that the exhaust isn't restricted in the least from the old broken cat, especially since it clogged the old muffler.

i'm not sure about the ppm efficiency difference between the ca emissions cat and the us 49 cat.. but that would allow the o2 to step out of bounds basically.

If the exhaust isn't restricted, maybe I will add an 02 sensor spacer.