The key fob will need to be reprogrammed to the vehicle as when the battery was replaced in the key fob, the key was reset. This is why nothing is working with the key fob. After replacing the battery in the key fob remote, you will need to reprogram the remote to the vehicle.

Do the following:

1. The vehicle must be off.
2. Place the new, unrecognized transmitter into the transmitter pocket with the transmitter buttons facing the front of the vehicle.
3. Insert the vehicle key into the key lock cylinder located on the driver’s door.
4. Turn the key to the unlock position five times within five seconds.

Reset the keyless entry remote to your Cadillac by pressing and holding both the “Lock” and “Unlock” buttons. Release the buttons when the power locks cycle automatically, indicating that the resetting process was successful. Turn the ignition back to the “On” position to exit the vehicle’s programming mode.

What to Do if There is No Key Detected in a Nissan Key Fob. Even if your Nissan fob battery is still good, there may be an instance where the vehicle does not detect it. In most cases, the battery is likely either low or dead, but there could be an issue with your Nissan’s remote key functions.

If the key fob does not connect with your car after a battery replacement, then it is a sign that you need to reprogram the newly replaced Key fob battery. Reprogramming is required to make your car remote function again.

Nissan Key Fob Programming Instructions

1. Sit in the driver’s seat of your Nissan. Close and lock the doors.
2. Insert your key in the ignition. Turn the key to “ACC,” turn it off and remove it from the ignition.
3. Insert the key into the ignition.
4. Turn the ignition key to “OFF” and remove it from the ignition when complete.

First, flip the key fob over, then push the small release latch. Pull out the hidden emergency key from the bottom of the fob. Insert the key in the driver’s side door and unlock it to enter.