it will go off depending on what caused it to light up. i unplugged the oxygen sensor to do a test. i put the wire back and after an hour of driving, the check engine/service engine light turned off.

 

Hey my light came on too. I took it to the dealer and they ripped me off. If your car is running fine dont worry about it. I guess if u dont tighting ur gas cap all the way (bull **** it know) a sensor kicks on bc a decrease in pressure.
no Joke!!!