Oil Pressure Switch

If the "OIL PRESSURE" indicating lamp lights up when the ignition switch is "ON" and goes out when engine is started and runs at idle, everything is in order. If "OIL PRESSURE" lamp does not light when ignition switch is "ON". Check switch, lamp and wiring.
If there is current flow when ignition switch is "ON" and if there is no current flow when engine is running at idle, the switch is good. If the switch is good, check the lamp and wiring.
Oil pressure switch operation pressure :

14.71-29.42 kPa (0.15-0.3 kg/cm² ,2.1-4.3 psi)

Fig 1: Identifying Oil Pressure Switch
Courtesy of KIA MOTORS AMERICA, INC.
Using 24 mm deep socket, tighten the switch to the specified torque.
Tightening torque

Oil pressure switch and sensor assembly:

8-12 N.m (80-120 kg-cm, 5.8-8.7 lb.ft)

Fig 2: Installing Oil Pressure Switch

Courtesy of KIA MOTORS AMERICA, INC.