For your safety, the automatic transmission has a shift-lock system which prevents shifting the transmission from P (Park) into R (Reverse) unless the brake pedal is depressed.
To shift the transmission from P (Park) into R (Reverse):
1. Depress and hold the brake pedal.
2. Start the engine or place the ignition switch in the ON position.
3. Move the shift lever.
Hyundai Sonata LF 2014-2019 Service Manual: Repair procedures
Replacement
1.
Disconnect the battery negative cable from the battery and then wait for at least 30 seconds.
2.
Turn the steering wheel so that the front wheels can face straight ahead.
3.
Remove the airbag module.
4.
Remove the DAB module.
(1)
Disconnect the air bag connector (A). ...
Hyundai Sonata LF 2014-2019 Service Manual: Components and Components Location
Components Location
1. Engine Control Module (ECM) 2. Manifold Absolute Pressure Sensor (MAPS) 3. Intake Air Temperature Sensor (IATS) 4. Boost Pressure Sensor (BPS) 5. Engine Coolant Temperature Sensor (ECTS) 6. Throttle Position Sensor (TPS) [integrated into ETC Module] ...