O2 sensor issues.

[RandyBoBandy]

Hey everyone I'm currently working on a 2015 tahoe. This is my friends truck. I had recently intalled a new engine. He also had a cattylist bank 2 below threshold codes.
Dealer also told him when he had it in for the engine diagnosis that his converters were shot.
So I replaced the cats and o2 sensors. Now I have codes for both sides being below threshold and while watching the 02 sensors on the scantool. As the CEL triggers the both Bank1 s1 and Bank2 s1 hav3 zero volts. While the others retain the voltage. Has anyone encountered this issue or have any direction for me. I do not have any manuals or wiring diagrams, and my scanner is a harbor freight special.

 

[Tahoe14]

@Doubeleive may have some insight

 

[OR VietVet]

Welcome to the forum from Oregon.

Did you recheck all your wiring connections and grounds? For both to be effected, there should be a common connection, like a ground.

 

[Doubeleive]

Hey everyone I'm currently working on a 2015 tahoe. This is my friends truck. I had recently intalled a new engine. He also had a cattylist bank 2 below threshold codes.
Dealer also told him when he had it in for the engine diagnosis that his converters were shot.
So I replaced the cats and o2 sensors. Now I have codes for both sides being below threshold and while watching the 02 sensors on the scantool. As the CEL triggers the both Bank1 s1 and Bank2 s1 hav3 zero volts. While the others retain the voltage. Has anyone encountered this issue or have any direction for me. I do not have any manuals or wiring diagrams, and my scanner is a harbor freight special.

might be a dumb question but have you checked the fuses?
any chance a wire got pinched during the engine swap?
otherwise your probably going to need to get a meter and check for a open circuit
I do not have the diagram for a 2015 @mikez71 or @swathdiver might have them handy

 

[mikez71]

https://ls1tech.com/forums/attachments/conversions-swaps/706021d1530209208-pinouts-wiring-diagrams-2015-chevy-truck-tahoe-4wd-v8-5.3l.pdf

Good luck! That wiring diagram is fun following the wire through different pages while changing numbers!
Page 3,...,7,8

Agree with Doub.
Both your non working sensors share the same fuse. Looks like O2 A, 15 amp.

 

[CrashTestDummy]

https://ls1tech.com/forums/attachments/conversions-swaps/706021d1530209208-pinouts-wiring-diagrams-2015-chevy-truck-tahoe-4wd-v8-5.3l.pdf

Good luck! That wiring diagram is fun following the wire through different pages while changing numbers!
Page 3,...,7,8

<SNIP>

Yeah, it's almost like they really don't want you doing that, right?!?