If the Smart Key is not working properly, try replacing the battery with a new one.
Battery Type: CR2032
To replace the battery:
1. Pry open the rear cover of the smart key.
2. Remove the old battery and insert the new battery.
3. Reinstall the rear cover of the smart key.
If you suspect your smart key might have sustained some damage, or you feel your smart key is not working correctly, contact an authorized HYUNDAI dealer.
Information
An inappropriately disposed battery can be harmful to the environment and human health. Dispose the battery according to your local law(s) and regulation(s).
Hyundai Sonata LF 2014-2019 Owners Manual: Good Driving Practices
Never move the shift lever from P (Park) or N (Neutral) to any other position
with the accelerator pedal depressed.
Never move the shift lever into P (Park) when the vehicle is in motion.
Be sure the vehicle is completely stopped before you attempt to shift into
R (Reverse) or D (Drive).
Do ...
Hyundai Sonata LF 2014-2019 Service Manual: Front Seat Assembly Components and Components Location
Component Location
1. Front seat assembly
...