Do SES (CEL) lights sometimes light on a timed basis?

I was wondering if the Service Engine Soon (or Check Engine) lights sometimes are set to come on when a component reaches a certain “age” rather than when it begins to fail? (I have a 2001 Saturn SL-1.)

Nope. The computer cares not (and knows not) how old somethings is. It only “knows” whether or not the signals it gets are within specs.

Given all of your questions though, perhaps you need a good, local, trustworthy mechanic to help you look over your various issues.

Actually, EDIT: I was answering with your post about the coolant temp sensor in mind (maybe you want just one thread?) There are “service engine” lights that are meant to tell you things such as when you should change the oil. These aren’t so much about “age” as they are about usage stats since maintenance was last done. You would have to look in your owner’s manual to verify what kind of light you are looking at. But, either way, there is nothing in the computer’s monitoring that will trigger actual error codes (DTCs) based on age.

Thanks! You have answered all my questions today. It is much appreciated.