After a couple of years of almost daily use, the battery inside the key fob remote control for the keyless entry system of a fourth generation (2016, 2017, 2018, 2019 and 2020) Kia Optima sedan can become weak or stop working entirely. Check out my DIY tutorial for the battery change procedure (with the compatible replacement part number) by clicking on the text link or thumbnail image below.
2016-2020 Kia Optima Key Fob Battery Replacement Guide
