I just bought a one owner 2003 3.8l auto Mustang from my mother in law. It is has 30,000 original miles. It is cherry in every aspect. However the check engine light came on and I found that the fuel sensor is the reason. The gas gauge was acting odd before the warning so I am not shocked. The question I have is it something I need to replace right away or can I drive it just being sure to keep a full tank? Please advise as I don't have the money to fix it if it can wait.