I am new to the Chevy forums, but I am pretty well versed in the automotive world. This time, however, I am at a little bit of a loss. I bought a new to me, 2015 Tahoe, 107,000 miles, lots of deferred maintenance. Check engine light was on, previous owner said he kept throwing in Seafoam that would turn the light off at each gas fill up. I bought cheap white box (Amazon) O2 sensors, worked fine for about 50 miles and then it started to really shake. RPM would drop to 400 or lower, sometimes come up, sometimes die. I pulled the battery cables off for 20 minutes, tried it again, ran great for 36 minutes. Then the stumbling started again.

Today I bought GM downstream (12657188) after it threw a code for both downstream O2 sensors. Bank 1 and Bank 2, Sensor 2. Installed, the new O2 sensors, problem persists. It was NOT like this prior to installing the new O2 sensors. Is it possible that both the up and downstream white box units are junk? Please advise.

 

Swapped out two of the downstream O2 sensors with the AC Delco, unhooked the battery and let it reset. Stalling problem went away, but now I have a fuel trim issue. I'm betting the upstream O2 sensors are crap too......