DTC P0660-00: Intake Manifold Tuning Valve Control Circuit/Open (Bank 1): General Description
WARNING: This page is about a different car, the 2021 Kia Soul. However, it is still accessible from the selected car via links, so may be relevant.
The Variable Intake System (VIS) is a device which varies the length of intake manifold to generate maximum power at certain RPM. The VIS lengthens intake manifold to improve the torque at low RPM when vehicle speed is low while it shortens intake manifold to raise torque at high RPM when vehicle speed is high. The PCM controls VIS using RPM signal.