How do you program 2009 sonata key?

To program a 2009 Hyundai Sonata key, you typically need a working key for the vehicle. Insert the working key into the ignition and turn it to the "On" position without starting the engine. After about 10 seconds, turn the key back to "Off" and remove it, then insert the new key and turn it to "On" for about 10 seconds. This process may vary slightly, so it's advisable to consult the owner’s manual or a professional locksmith for specific instructions.