2dubs

I have an 06 chevy aveo with 98k miles on it.

I recently started firing a p0420 code. Yay.

I replaced the cat with a cheap aftermarket (I know, but I can only do so much right now). This one to be exact:

Chevrolet Aveo 1.6L Front Catalytic Converter 2004 2005 2006 Stainless OBDII

Straight out of Canada.

My p0420 code continued.

I replaced the downstream o2 sensor with a Bosch replacement from partsgeek.com

I continue to get the p0420 code.

I have obdwiz and a reader... so I can see most of the info you mechanic guys can, I assume. I'm sure yours is better.

From what I read on the o2 sensors...

At idle:
Upstream - between 0.0v and 0.9v
Downstream - average 0.6v, occasionally runs below this, rarely maintains below 0.5v

At 4k in neutral:

Roughly the same as above. Upstream gets a bit more erratic. Downstream remains roughly the same.

Driving:

From what I can tell (hard to drive and watch), downstream is ranging over 0.6v. Upstream can push up as high as 1v, but downstream fluctuates between 0.8v and 0.4v.

If I floor the car in neutral, it sputters for a split second before the RPMs jump up.

I'm hesitant to throw any more parts at the car. I feel like I either have a bad CAT or I don't know something that can cause this.

Does anyone have anything besides I got a bad CAT?

I attached my .tdl recorded data in a .rar archive. If you have obdwiz, you should be able to open my recorded data and see what's happening.

Thanks guys.

2dubs

My father in law insists I replace the upstream o2 sensor, too.

Thoughts?

tech2

its possible that a lazy pre cat 02 could set a false dtc. I have never seen it on a chevy (but this is a daiwou)as usually if the 02 is bad an 02 dtc sets.


the cat monitor uses 02 cross count comparisons for determining catalyst efficiency.
Chrysler products do have this issue when you install one new with one old sensor.
fyi there was some pre cat 02 sensor problems associated with this model so what are the fuel trim % at.


if they are adding fuel, check for a torn intake snorkel. if the snorkel is ok it may need an 02


but yeah cheap cat could very well be the problem. its a toss up not being able to view live data.