O2 sensor readings

[temperingloser]

Just wondering if anyone knew if these reading seemed right for the 02 sensor in the snapshot. I have attached the snapshot to this thread.

[Tech II]

Yes, they are ok.......

The pre should be constantly changing.......

The post should change slowly.........

When the post "mirrors" the pre, then the catalyst is not working....

[temperingloser]

it seems to come close to that when I am driving. it popped the p0420 the other day and I reset it and it has not come back. Just making sure that is a non issue.

[Stealthee]

0420 can be a random bitch. I have had my Grand Prix for a little over 5 years. It threw a 0420 once a few months after purchase. I cleared it and it didn't occur again for a long while. I even replaced the factory downpipe/cat with a high flow ZZP 3" catted downpipe and didn't start getting the code again until last fall. There was another code along with it that told me the 02 was dying so I replaced it.

Replacement turned out to be an issue though because the o2 was partly rusted into the o2 bung. When it broke loose it must have partially stripped the threads because the new o2 would get to a point where it was tight, then get loose. I got it as good as I could and left it.

Now I can drive for hours and not get the CEL, but if I get into stop and go traffic/stop lights, it will pop if I idle for too long at a stop light.

I'm probably going to just weld a new o2 bung on to see if it fixes my issue.

[Tech II]

Well, if it does mirror while driving, it's probably on it's way out......you don't say the year/mileage......check your warranty for a possible replacement....

There are also these O2 simulators....illegal(not all states, because not all states have emission testing), but they work....if your conscience doesn't bother you....screw the earth...mine does....