Definitely want to check the plugs and harnesses on your new upstream sensors. If everything looks good, I'd throw a set of known-good-brand sensors in and see if that fixes it. Delco ones work, and I've had great success with Bosch sensors. Recommend at least browsing Rock Auto to verify you have the proper sensor part #s before ordering from your vendor of choice, just in case there's multiple sensors that'll fit into the same harness.
^ X2. For any sensors on these trucks I'd stick to GM OEM/ACDelco whenever possible.
I'd also check your wiring and connectors to make sure that nothing got pinched or damaged when you did the exhaust work.
Agreed in general, though specifically for O2 sensors I've never had an issue with any Bosch O2 sensor I've put in my GMT400s or other vehicles.
Everything else, especially CPS and TPS, I stick with OEM sensors.
If you don't have catalytic converters installed, you will have a check engine warning. On a O2 sensor system with upstream and down stream sensors. The upstream is watching the mixture, like most have since beginning. The down stream , or after cat sensor is monitoring cat health. Tougher pollution laws. If delete the cats , they don't pass health check, constantly thinks cats are no good. Have you retuned pcm for removed cats?
Some vehicles are picky about brand. Some aftermarket are crap. I use NGK/ NTK they work.
Exactly my thought. You can't do a cat delete with stock sensors.
There is a cheap possible workaround... Go on Amazon or ebay and buy some "sparkplug defouler" spacers. Install these between the downstream sensors and the pipe. This moves the sensor element far enough out of the exhaust stream to fool the computer.
It's always a good practice to use ACDelco electronics in these vehicles, though I have had good luck with Bosch sensors for years.
Don't let anything touch the sensor element and contaminate it before install.
Both his codes listed are for upstream sensors though - shouldn't matter if you have cats or not, you need working #1 sensors on both banks or it'll run open loop forever and throw the above CELs at'cha.
