I have a 00 avalon whic I just bought a month aga I had a limited 30 guarantee but it just expired a few days ago. the car is running the same as when i bought it nothing has changed and the check engine light just came on any suggestions on what can possible be it has 128k miles? please help. I am not a very mechanichaly inclined person and dont want to be taken advantage when i take it to the shop id like to have some kind of direction. thanks