Report "Why would my check engine light go off by iteslf? I have a 2006 Kia Rio. Three weeks ago the check engine light came on with code P2096 and P0300, 0301 and 0302. Mis fire in two cylynders and oxygen sensor. I had a tune up, replaced the heated oxygen sensor and cleaned the fuel injectors. They said that would probably take care of both codes. A week later the same codes were back. They cleared them. The light came back on two days ago so I took it back. They said there was only one code this time and it ws P2096. They said mabey the heated oxygen sensor was defective and was still under warranty with Autozone. They didn't have time to fix it until next week. They cleared the code. Yesterday I drove 100 miles one way and the light came back on. By the time I drove the 100 miles back the code had cleared itself. Why would it go off by itself? I read that it takes time for the computer to get the message that the problem has been fixed. Could this be what happened? Should I take it in or wait to see if it comes back on? Thanks, Shirley"