Sit in the Hyundai Sonata with the keyless entry remote that you wish to program and the vehicle ignition key. Shut the door.
Open the cover of the alarm system control module. The alarm system control module is located right below the fuse panel on the driver's side of the vehicle.
Turn the memory switch, located in the alarm system control module, so that it is on the "Off" setting.
Place your key in the ignition and switch the vehicle to the "On" setting. Do not start the car. Wait exactly 60 seconds.
Turn the memory switch in the alarm system control module to "Set."
Press "Lock" on the keyless entry remote and hold the button down for approximately 60 seconds. This syncs the signal from the keyless remote to the vehicle signal.
Release the "Lock" button on the remote and return the memory switch to the "Off" setting.
Turn the ignition to the "Off" setting and remove the key. Get out of the vehicle and verify that all buttons on the keyless entry remote work.
Repeat this process if it did not successfully program the first time. Ensure the batteries work and the remote is in working condition if the remote fails after subsequent programming attempts.Keyless entry remotes are standard on many vehicles sold today. These remotes allow you to lock and unlock the vehicle from a distance, making it much harder to lock your keys in the car. If your current keyless entry remote stops working or if you lose it, you can purchase a replacement remote from a Hyundai dealer or from an online retailer. Once you receive your replacement keyless entry remote, you will need to program it so that your particular vehicle responds to the signal from the new remote.