Where do you get an oxygen sensor?

Hello, the "oxygen sensor" is often called an "exhaust gas oxygen sensor" or an "air flow sensor" or a "heated exhaust gas oxygen sensor". I would strongly recommend an original equipment Kia sensor if at all possible. There are aftermarket alternatives, but in my experience, an original equipment component can be far superior in performance. You will need to specify if the sensor is before or after the catalytic converter. Why are you seeking one?