If the fuel filler door does not open using the remote fuel filler door release button, you can open it manually. Pull the release located on the left side of the trunk compartment.
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] ...
Hyundai Sonata LF 2014-2019 Service Manual: Starter Relay Repair procedures
Inspection
1.
Turn ignition switch OFF and disconnect the negative (-) battery cable.
2.
Remove the fuse box cover.
3.
Remove the starter relay (A).
4.
Using an ohmmeter, check that there is continuity between each terminal.
TerminalContinuity30 - 87NO85 - 86YES
5.
Apply 12V ...