Replaced 1x o2 sensor. 4 dives later I got CEL with P0174
 

V8

I replaced Bank 2 sensor 1 about 2 weeks ago because I had a code.
I think that was P0420 but I don't recall exactly.

I've only driven it a few times since then. 2x 1 mile trips. 2x 10 mile trips. On the last trip I got a CEL. So I pull codes and found multiple that I did not see before I changed the o2 sensor.
I also changed the radiator fan clutch and some coil packs if that matters.


I did feel like it was running a little rough at idle on drive 4 after I noticed the CEL but I didn't notice this at start up.
I did not notice that on drives 1, 2 or 3 but wasn't looking for it either (and 2 were so short).
Did not notice exhaust smell but didn't walk behind it while running.
Would go sniff it right now but it's storming.

A few internet suggestions were:
-Replace all the o2 sensors (the other 3) or at least the other front side front sensor.
-Clean the MAF sensor
-Replace/clean Fuel Injectors
-Clean TB
-Oil Filler Cap
-Gas Cap


Any other ideas?

Seeing as how mine popped up right after I changed 1 sensor, I am leaning towards it being an imbalance in the other sensors.
So I am ordering those but they won't be here until the 19th. Ugh!


EDIT: Found a few similar threads I am linking here that I am still reading through.
Some of the above ideas are echoed in these:
P0174, Rough Idle & Strong Exhaust Smell
Help needed- Fuel pressure test persistent p0174
P0174

Mine at 230k miles had the recurring code.
Yes, it helps to replace all the stated maintenance items, but finally when I replaced the cats, I think the culprit was the exhaust donuts slightly leaking. Hardly even noticable in the car, but likely the culprit to the codes.

Worth checking and or replacing

Ahhh. OK.

Did you go with OEM cats?
If not, what did you get?

EDIT:
I'm looking on RockAuto and a little confused.
Do we just have the 2 cats that are integrated with the manifolds or is there a 3rd one?

Looks like there is a 3rd...
Not sure how the system checks that because don't we have 4 o2 sensors ... one in front of and on behind the integrated cats?
So how does it know if that is even in place?

the catalytic converters in question are the 2 integrated into the exhaust manifold.
If you have an exhaust leak up top where the upper O2 (Air fuel) sensor is reading it's possible that is the cause.

failed/failing cat will read throw a code for a system below efficiency code (which is also common for a bad lower o2 sensor).

To answer your question on why it took driving around is because before a fault code is logged it goes through a few cycles to make sure the reading it was seeing wasn't an anomaly, not to mention it probably likely that you pulled the battery when doing this work? If so, that would have reset your system and it needs to go through a few driving cycles to reinitiate itself.

I got the $400 per manifold cats. Don't know if they were any different but I didn't want the cheapest ones.

That may not have been the issue despite replacing them as there was a slight exhaust leak just before the O2 sensor.. so yea

Easy enough to do the donuts and even manifold to head gaskets first and save $800