1. Disconnect the wire from the negative terminal ("-") of the battery.
2. Remove the door sill trim.
3. Loosen the lower anchor bolt and remove the lower trim of the central pillar.
4. Loosen the upper anchor bolt and remove the upper center pillar trim.
The original can be read on the resource [HYUNDAIBOOK]
5. Remove the upper and lower plates and the front seat belt mechanism.
6. Unscrew the two mounting bolts and remove the sensor, disconnecting the connector.
Install the new sensor in the reverse order.
After installing the sensor, turn on the ignition on the dashboard, the control lamp should light for 6 seconds, then go out. This indicates that the green sensor is done correctly.