Greetings. New here and hope all are well. My '11 2500 shows codes for both bank upstream sensors as well as the dreaded P042 . . .yea, I know. The local inspection station tells me that the numbers (PPM?, etc) presenting on his machine would still fail with new sensors. The sensors aren't as much of a concern as the cat($) . . . apparently there are three. Any members had to contend with this one? The guy eluded to a front vs rear heat test for each one . . . ok fella . . . if you say so (LOL). Soo, replace just one "bad one"? All three" The piping is in great condition so I'm reluctant to just go with the three into one. To boot, few reputable places around here will consider touching anything other than OEM even those that are CARB compliant (Walker, Flow Master, Magna). Unfortunately I don't have access to my buddie's lift anymore so I can't facilitate this one myself (too old & broken to play "creeper jockey" LMAO). Intel & experience would be greatly appreciated . . . as I attempt to figure out why the damned temperature gauge has stopped functioning with a new thermostat just weeks ago UHHG! This is "Murphy's LawFARE" in real time . . . . . JJFII

 

I can't help with the question on the cats and O2 sensors, but the temp gauge not working is likely the sender on the back of the engine block. It can be replaced fairly easily with the right "temp sender socket" and a universal joint on your socket extension.

I am thankful I've not lived in a state with emissions inspections since 1996...

 

Hey j, thanks for getting back. Looked a bit more into it last night and hard pressed to find intel or vids specifically for the 6.0. Have a window of lead time though, looks like a few days of heat wave next week . . . low to mid 40's LOL

 

Well, I went and did a little reading, and some of the articles online about the P0420 (I assume that is the code you meant) indicate that while the code is relating to the bank 1 catalytic converter, it *CAN* be triggered by failed O2 sensors. I would personally replaces those (easy and cheap) first, see if the code is still present after a few drive cycles, then worry about the cat(s).

This is one of the articles I found on the subject. While it is most likely the cat, its worth looking at the other possibilities.

https://mechanicbase.com/trouble-code/p0420/

 

Great, thanks again . . .

 

Well, replaced the coolant temp sensor with an AC Delco and the gauge is functional again. That said, after 20 min at idle I estimate 185 +/- just a titch for the temp. The numeric increments on the gauge are 160 at rock bottom, then just ---- between that and 210 so it's hanging right about on that line. I've seen 195 - 200+ as normal for the 6.0 however, the thermostat was replaced just recently with some ps repairs so that might play in . . .

 

185F or so after 20 minutes is in line with where I think my Silverado with its 4.8 sits. I think in summer when driving for a while, mine approaches the 210 mark, but has never quite reached it.