Some vehicles are equipped with cable drive systems. In this system, the throttle body is controlled by the TPS (Throttle Position Sensor), the ECM (Engine Control Module), and an electric actuator motor in the throttle body.
The ECM uses the information provided by the TPS sensor to control the actual position of the accelerator pedal. When the actual throttle position is not within range, the diagnostic code P0638 OBDII is set. This DTC code refers to bank number 1, this is the side of the engine where cylinder number 1 is located.
Most vehicles use one throttle body for all cylinders and are generally not repairable, they have to be replaced.