Service Engine light and Oxygen Sensors

[Riggodeaux]

My 'service engine soon' light is on and I've been reading up on possible causes. I will run the codes this weekend. I anticipate cleaning the MAF sensor, regardless, but since the CCV components were replaced 14 months/24k miles ago, just before I bought the vehicle, I'm assuming [perhaps erroneously] I won't have to do the CCV job. One possible source I've seen id'd is an oxygen sensor - and I see reports that replacing them [x4, parts cost maybe $280] as a 100k mile maintenance item. I'm overdue for that, if so, and need to do spark plugs, as well, due on the same schedule. Have any of you done the sensors as a 100k miles preventive maintenance item? I have viewed a couple of good videos on this DIY. Any tips on which codes point to the CCV/vacuum leaks, as opposed to the MAF or O2 sensors? Thanks in advance for any guidance.