The "check engine soon" light came on after I had the fuel pump and lines replaced due to rust and gas leakage. After the replacement, the light came on. My mechanic dropped the gas tank again to check for a problem, but was unable to pinpoint issue. No problem with mileage or the car running. Due to the light, VA failed the car for the emissions test. Reset the light, and it hasn't come back on yet.
Just recently brought my 2002 Saturn L200. After putting gas in it for the first time, my check engine light came on and hasn't gone off.
Loose gas cap caused check engine light to come on.