Bad Cat Or O2 Sensor?

[siml8r5]

Got a weird issue. Got P0430 code from the Computer after replacing the intake manifold gasket. Looking at the O2 sensors at Temp, the O2S11 fluctuates from .1 and .9 millivolts, O2S12 stays between .82 and .90 millivolts. O2S21 fluctuates from .1 to .85 and O2S22 ALSO fluctuates. Shouldn't the O2 after the cat stay around .85 or so? I'm thinking it's a bad O2 sensor... Thoughts?

[Nytemare]

You could have gotten something in the intake from cleaning the gasket off and its burning off now...give it a couple days, get the code reset than see if it comes back. P0430 is your bank 2 rear O2 sensor.

[minibike132]

You could have gotten something in the intake from cleaning the gasket off and its burning off now...give it a couple days, get the code reset than see if it comes back. P0430 is your bank 2 rear O2 sensor.

 

 

+1 wait a few days then recheck. I would say that if the post cat HO2S is as active as the front and all the contamination gets burnt out you need a cat, a bad O2 does not become more active it becomes less active.

[siml8r5]

Well, I replaced the O2 sensor on the right side behind the cat. Which, I assume was the active one since the P0430 points to the right side or Bank 2. If that's not the bad one, I could always take the one I took out and swap it with the left side and see what that does. After I cleared the code, I drove it for an hour before the SES light came back on. The catalyst test seems like it only completes when the truck comes to an idle after a good drive... at least that's what it seems like. Also, after an hour, the EVAP test and the O2 Sensor Htr test was INC on the scan tool...