Transmission

Probably not as that is a torque converter clutch circuit code. Usually it means the solenoid is bad or stuck.
It takes a scan tool and pressure gauge to test the system and trace the problem.

Thank you. My mechanic said he was going try to flush it first to see if that helps but maybe I should just tell him not to. (Can you even flush the transmission on a kia sportage? my friend said you can't because of the way it's built.) The dealership said they found metal shavings in my fluid and that I need a whole new transmission.

You can flush it but it normally doesn't help. That trans isn't "user friendly" when it comes to service. That is what many auto companies are trying these days, replace a large component instead of repairing it.