Operating Door Locks from Outside the Vehicle
Mechanical key

If you lock the driver's door with a mechanical key, all vehicle doors will lock. If you unlock the driver's door with a mechanical key, the driver's door will unlock and the passenger doors will unlock according to the current two press unlock setting.
Once the doors are unlocked, they may be opened by pulling the door handle.
When closing the door, push the door by hand. Make sure that doors are closed securely.
Remote key

To lock the doors, press the Door Lock button (1) on the remote key. Press the Door Unlock button (2) on the remote key, the driver's door will unlock. If you press the Door Unlock button on the remote key again within four seconds, then all the doors will unlock.
Once the doors are unlocked, they may be opened by pulling the door handle.
When closing the door, push the door by hand. Make sure that doors are closed securely.
Information
Immobilizer System
Smart keyHyundai Elantra AD (2016-2020) Service Manual: Accelerator Position Sensor (APS) Repair procedures
Inspection
1.
Connect the GDS on the Data Link Connector (DLC).
2.
Turn the ignition switch ON.
3.
Measure the output voltage of the APS 1 and 2 at C.T and W.O.T.
Specification : Refer to "Specification"
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Hyundai Elantra AD (2016-2020) Owners Manual: Pre-tensioner seat belt (Driver and front passenger)
Your vehicle is equipped with driver's and front passenger's Pre-tensioner Seat
Belts (Retractor Pretensioner and Emergency Fastening Device System). The purpose
of the pre-tensioner is to make sure the seat belts fit tightly against the occupant's
body in certain frontal collisi ...