I have a 1995 blazer and the service engine soon light has been on ever since i bought it. i have had it scanned but every time it says there are no codes. I'm assuming its just some stupid emissions thing but was curious is anyone else has this problem. Sometimes the light will go off but normally comes back on the next day. Thanks for any info.

 

Not all code scanners are the same. Some can read more than others. Also, you should look to see what generation of the on-board-diagnostics (OBD) it has; 1, 1.5, or 2.

 

I had this exact issue with my 2000 Blazer. Ended up being the cat converter.