This warning light illuminates:
If there is a malfunction with the AFLS:
1. Drive carefully to a safe location and stop the vehicle.
2. Turn the engine off and restart the engine. If the indicator light remains on, have your vehicle inspected by an authorized HYUNDAI dealer.
Hyundai Sonata LF 2014-2019 Service Manual: Front Seat Outer Shield Cover Components and Components Location
Component Location
1. Front seat outer shield cover
...
Hyundai Sonata LF 2014-2019 Owners Manual: System setting and activation
System setting
The Driver Attention Alert system is set to be in the OFF position, when
your vehicle is first delivered to you from the factory.
To turn ON the Driver Attention Alert system, turn on the engine, and then
select 'User Settings → Driving Assist → Driver Attention Alert → ...