SRS and OPDS Codes in '07 Odyssey

So I just bought an '07 Odyssey with a clean title, and the airbag light came on a few weeks later.
Initially, I thought the battery might be the issue (because of another code, that I cannot now reproduce) - but that tests fine and so does my alternator (at least, that's giving the appropriate amount of voltage when the car is on).
Here are the initial codes I got
I thought it might be something with the seat wiring harnesses or sensors, so I unplugged the front seats and got these codes:
What's puzzling is that, after unplugging the seats, I did not get the SRS 58-A0 code. I cleared the codes and scanned again, and still it did not come up.
I can't find ANY of the original three codes in any list online, but my thought is that maybe the OPDS 42-00 has to do with the passenger side impact sensor, the OPDS 71-02 with the driver seat position sensor. I cannot for the life of me find anything on the SRS 58-A0 code.

So, has anyone experienced anything like this? Any advice on how to troubleshoot further? I want to avoid shelling out hundreds of dollars just to diagnose a sensor a problem that I might be able to fix myself.