I have an '04 Envoy SLT. The check engine light recently came on and my husband suggested I check to make sure the gas cap was secured tightly. It was "stripped" and wouldn't tighten. He replaced the gas cap and the light has not shut off. I've checked the forums and have noticed that there are "codes" to indicate the reason the light is on - can someone tell me how I can find out if there is a code for the reason my light is on? Also, any suggestions would be appreciated. Thanks - there is also a wealth of info on this forum!