Honeslty, the reality is that the check engine light only comes on when there is a consistant issue in a sensor. This then requires a specia ltool to read the logs of the car's mini computer to see which sensor is giving off the error. Some are important obviously. Others are less so and can be ignored if wanted.
such is the case with my car.
The light is on for a sensor that measures something, but isnt necessary for the car to run. The car will run fine without said sensor. The cost to replace it? Over $400.
I just dont like what they've been doing with the sensors since 2000, where if a sensor is just removed, the light stays on because its missing.