Was driving yesterday and suddenly triangle, check engine, (!) and VSC lights came on. I stopped and restarted my 2005 prius, but red triangle and check engine light still on. Car drives the same, no problem at all. My tank was half full, I pulled to gas station and filled the tank, and the lights went away. So I thought that I didn't put the gas cap tight enough. Today I was driving home and the same thing happened, all 4 light came back. I filled my tank again and lights went away. Does anybody know what the problem is. Could it be a bad gas cap?