You can't turn the check engine light off, not even by unplugging the battery. It is a computer wired vehicle and the computer has pulled a code meaning something is not right somewhere. Take it to the dealership and ask them what the code is and have them clear it, but if you don't fix the problem it will continue to pull that same code. It is probably 50.00 max for them to clear the code. You can't do it any other way.