I've owned my Envoy for about 2 months now, no problems. I drove about 100 miles today and as I was on my way home, sitting in Seattle traffic, my "Check Engine" light came on shortly after my "Low Fuel" light. I didn't notice a difference in the way it was running and I'm hoping it's a gas cap/vacuum issue. I tightened it and will find out tomorrow. Otherwise, O2 sensor, maybe? I have close to 120,000 miles. Not very familiar with these engines but looks like I'm starting to very soon. Could be a large number of things, I hope none catastrophic or bank busting. Any ideas?