We just answered an inquiry from an individual who bought a 2004 Nissan Sentra and was looking for a remote to use with that vehicle. Here is our response:
The correct factory keyless entry remote for a 2004 Sentra is Remotes Unlimited part 800-1800, shown at the following link:
2004 Nissan Sentra remote
However, not all 2004 Sentra sedans were equipped with factory keyless entry, so before you buy a replacement remote, you should confirm that there is a factory keyless entry system installed on the vehicle. You can call a Nissan dealer, give them your VIN, and they can tell you. Or, if you send us your VIN we can check for you.
Please note that there is a very common Nissan remote that looks exactly like the one you need and which is sold in many auto part stores. However, that part will not work on your 2004 Sentra.
If your vehicle does have factory keyless entry and you do buy a remote for it, you will be able to program the system yourself to accept the new remote. Remotes Unlimited provides free programming instructions and technical support with part purchase.