P1553 on a Kia means the engine control module (ECM) has detected an abnormally high voltage on the opening coil circuit of the idle air control (IAC) valve. The ECM expects a specific current draw and voltage drop when it commands the valve open, and a high-voltage reading tells it the circuit is not completing the path to ground as designed. This typically points to an open circuit, a failed coil winding, or a poor connection rather than a mechanical idle problem.
Guidance is general and written for Kia vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.
Get the app
Quick access from your home screen.