If your transmission light comes on, your first thought is probably the worst one: does this mean I need a new transmission? Sometimes, yes, and that's the honest answer. A transmission code can mean the transmission itself is failing, and in those cases the sooner you catch it, the better off you are. Before anyone talks about a replacement, there are other things worth checking first. A code tells us something is wrong, but it doesn't tell us what or how much it'll cost. That's why we diagnose the problem before we recommend anything, instead of jumping straight to the expensive answer.