2004 LEXUS IS300 Remote key must be cut to match your original key before you can use it. Not all locksmiths or dealerships have the proper equipment to cut high security remote keys, so you will need to call around before purchasing. If you are unable to find anyone to cut the key for you, we offer a key cutting service for $29.95. Please see the listing In Lexus category for more information. Once the new remote key is cut you can program it by yourself if you have one master working key (not valet), you can use the printed programming instructions that we send to make the remote key work for 2004 LEXUS IS300. The instructions are very easy to understand and can be performed in less than 2 Min. If you have lost all Transponder Chip Keys or remote keys for the vehicle you will need to contact an automotive locksmith or dealership to discuss your options. This Lexus Remote key comes with Brand new battery Installed and is tested for functionality before sending.