I had a code back in the early summer that said the upstream sensors were struggling, so I replaced with new Bosch sensors and today this popped up. There's no way the Bosch sensors are already bad or were DOA? Also... might as well ask the dumb question... upstream is the bank of sensors closest to the engine, yes?

 

Yes. Sounds like it's time to chase wiring, maybe some vermit got to it and it shorts out occasionally.

*fault is not currently present*

 

New, additional code thrown tonight and the P1000 language changed to 'signal missing'

 

What brand O2s? Bosch are known to occasionally be bad out of the box. It's happened to me, and to others as reported on this forum.

 

bosch :/ I’ll order another and try again

 

Yeah, bad out of the box is why I went to buying locally, so that I could exchange them easily. Thankfully I haven't needed one in five years. (Did I just jinx myself?)

Several people on this forum have reported better results with Walker O2s instead of Bosch.

 

Closing out this thread with the resolution - sure enough, DOA Bosch O2 sensor. New one in and so far the codes haven't returned.

 

My NTKs have been great. If the Bosch fail you again, go NTK.

 

Or Walker. Have used multiple Walker sensors on two different trucks and haven't had a failure yet.