I know huh!
You'd think check engine light would come on much easier, 2 trip detection logic for ya, I think it's garbage, I want to know when there is the smallest issue, not months down the road when the light finally comes on.
My friends sentra I'm working on, had the air intake hose cracked for many many months before check light came on. He took his car to pep boys for a tune up and a "diagnosis" 'mechanic' told him, "your o2 sensor is going out, needs to be replaced soon". What an a** hat. He said that because he most likely seen the o2 code coming up as intermittent. The o2 was and still is working perfectly fine.
If your able, read your engines data, not the codes.