You are able to program 2003 LEXUS GS430 Transponder Chip Key by yourself if you have one working MASTER key (*Has a black rubber head, or is a remote head key). It will first need to be cut to match your original key at an automotive locksmith or the dealership. Once the chip key is cut, you can use the printed programming instructions that we send to make the key work for your vehicle. The instructions are very easy to understand and can be performed in less than 30 seconds. If you have lost all Transponder Chip Keys for 2003 LEXUS GS430 , you will need to contact an automotive locksmith or dealership to discuss your options.