How do I change a battery on a 2004 Lexus ES330 without loosing any codes, etc? Thanks

I can only think of one way that would ensure you not to lose power to the computer. That would be to hook a pair of jumper cables to a good battery and to the cars cables then disconnect the old put the new in and hook it up withe out knocking off the cables. Just keep the wires away from each other. 2 or more people is very helpful!
Best of luck to ya!