The secondary O2 sensor doesn't affect engine performance.

You can try doing voltage drop tests on the wires in question. It is simple to do. Do you have a volt meter?

 

In my case, after having no luck finding anything, I removed the ground wire entirely. Holding the entire wire in my hand, the middle part didn't seem as flexible as it should be.

In hindsight, I might have been able to check that by measuring voltage drop while moving the wire around. Flex it a certain way and it would disconnect, flex it back around & it would have continuity again. It really drove me nuts because that's the last place you'd expect a problem.