DTC P0121: Throttle Position Sensor Circuit Range/Performance, DTC P0122: Throttle Position Sensor Circuit Low Input Or DTC P0123: Throttle Position Sensor Circuit High Input: Description
WARNING: This page is about a different car, the 2002 Nissan Xterra and 2002 Nissan Frontier. However, it is still accessible from the selected car via links, so may be relevant.
The TP sensor responds to the accelerator pedal movement. This sensor is a type of potentiometer which transforms the throttle position into output voltage, and emits the voltage signal to the ECM. In addition, the sensor detects the opening and closing speed of the throttle valve and feeds the voltage signal to the ECM.
Idle position of the throttle valve is determined by the ECM receiving the signal from the TP sensor. This sensor controls engine operation such as fuel cut. The wide open and closed throttle position switch, which is built into the TP sensor unit, is not used for engine control.