DTC P1688: Immobilizer Lock: General Description
WARNING: This page is about a different car, the 2021 Kia Soul. However, it is still accessible from the selected car via links, so may be relevant.
Immobilizer (IMMO): A security device that permits vehicle to start only when the password code of key (transponder)/IMMO/EMS matches with each other to prevent vehicle theft.
The IMMO makes the IMMO inoperable when an invalid password code value (PIN code and password) is input.