sokoloff made me aware that auto zone would do the code check for me. i called auto zone this am to see if they would have time to do this if i brougt the car in within the hour. the answer was affirmitative. on the way their. approximately 20 miles, i stopped to fillup with gas. when i went to remove the gas tank cap i notice the cap was just sitting on the tank. my wife was driving the car the last time gas was put in the car. she said since she did not know how to do this, she had her lady friend riding with her put the gas in for her. i filled the car with gas an put gas cap on properly. on the way to auto zone the ligft went out. i asked the person at auto zone if the gas cap was left loose could this cause the light to come on? his answer was yes. i forgo any additional check but will return should the light come back on. any additional thoughts you may have will be appreciated