It could be the sensors, but on newer cars the software can usually tell if the sensor isn’t working. My guess with that code it is the cat that has failed. Or is failing. The cause of the failure could be something wrong with the engine of course. But it wouldn’t be that surprising that a cat would fail at around 100K.
I guess what I’d do is bring all the routine engine maintanence recommended by Honda up to date, and if that didn’t fix it, I’d replace the cat and probably both sensors (before and after the cat) at the same time. That should get you through the smog test with flying colors.
If you want to try to fix it on the cheap, just replace the sensors. There’s chance – slim perhaps – that will be good enough to pass the smog test.