O2 sensor trouble

[Schurkey]

Wouldn't it be a thousand times easier to go to a muffler shop, have them weld a second bung after your single converter, and just stuff another sensor right next to the one that's already there?

The computer is looking for two downstream O2 sensors. Give it what it wants.

 

[stutaeng]

I have a feeling it's gonna end up being some kind of wiring problem yeah. What's interesting is that P0140 is a pending code, while P0160 is an active code. Gonna do some a voltage test and probably end up making a custom O2 sensor harness. End goal is to redo all the wiring in the truck anyways so

The harness gets messy for the grounds right around where the bellhousing goes. There's a bunch of ground wires spliced connected to more wires that are spliced again.

I undid a harness once thinking I could modify the O2 sensors (for another harness) and wound up with a big mess. Luckyly, my plan wasn't even an option because the wiring was for different years, so I scrapped the harness...

I would be checking for ground on the connectors, along with 12V+. I think black is ground and all pink wires are 12V back to the fuse block. And another wire from the sensor does go back to the ECU. You'll need a wiring diagram.

 

[Jesse_Wenting]

The computer is looking for two downstream O2 sensors. Give it what it wants.

I don't mind having the code thrown for the driver side sensor because eventually when I make a custom exhaust I want to go back to dual cats. I don't get why there's a problem with the passenger side sensor is all

The harness gets messy for the grounds right around where the bellhousing goes. There's a bunch of ground wires spliced connected to more wires that are spliced again.

I undid a harness once thinking I could modify the O2 sensors (for another harness) and wound up with a big mess. Luckyly, my plan wasn't even an option because the wiring was for different years, so I scrapped the harness...

I would be checking for ground on the connectors, along with 12V+. I think black is ground and all pink wires are 12V back to the fuse block. And another wire from the sensor does go back to the ECU. You'll need a wiring diagram.

Just finished. Black has a good ground connection, Pink is hot from the ignition switch and has 12v when appropriate, tan/wht & purple/wht both have good continuity from the O2 connector to the ECM pins. Starting to think I just got a defective O2 sensor

 

[honkon]

What did you use to test the wires?
Have you monitored live data with an obd scanner?
You could have a pin fitment issue. Do a very thorough visual inspection of the o2 connector.
Also I'm still not clear on why you want to entirely redo the wiring in the truck?

 

[GoToGuy]

GM "gangs or rather bunches" grounds to a single point on many sensors, electrical functions. It's a repair diagnostic and effeciant assembly concept. Centrally located grounds versus hundreds here, there, over under......the wiring diagrams identify wire colors and wire numbers and drivabilty manual identifies connectors in last chapter.

 

[Jesse_Wenting]

Also I'm still not clear on why you want to entirely redo the wiring in the truck?

I'm just that kinda guy tbh.

What did you use to test the wires?

Auto-ranging multimeter

 

[GoToGuy]

Are you using NKG/NTK O2 sensors? As much as i want to make every penny scream as it leaves fingers, there are known widespread issues with less than adequete performance and quality on aftermarket O2 sensors. OBD 1 has known to loss it mind with some after market sensors giving codes or failing emss' test with high oxides where none exist. Not all, just the typical it happened enough so it got a closer look. I tryed to cheapout on wifes minicooper fwd before cat. And it didn't play well. Got the NTK and of course nothing like doing it twice to be perfect.
I agree that an added second bung to "play make believe" with the ecm would be easier. And when you go back to the "Y" with dual cats you'll allready be in place, time saved. There are afermarket " cat delete ghosting" items but if your end plan is get the original design back the logic goes back to adding another O2 position allowing normal operating parameters. We'll just pretend there's two cat converters for the ECM. Based on you described that's where I'm leaning. Good luck just my thoughts.