guages are a common problem with impalas, unless you live in a wintry environment and would like to know when your engine is warmed up, it doesn't really effect anything, i guess you could say its good to know if your car is over heating but in a 2004 you won't have that problem, overheating is not going to happen, unless your radiator gets busted or you don't get your fluids changed, but everytime you get an oil change your fluids are checked so that won't be a problem, if you have the money and really want i fixed than you might have to change the entire cluster, because its easier to do that, however you can buy an aftermarkert temp guage and just plug it into the wire and mount it, but that is kind of tacky, i would just ignore it. and save my money