DTC P0121: Throttle Position Sensor - Range/Performance Problem: Description

The Throttle Position Sensor (TPS) responds to accelerator pedal movement. TPS is a potentiometer which transforms throttle position into output voltage, and emits voltage signal to the ECM. In addition the sensor detects the opening and closing speed of the throttle valve and feeds voltage signal to the ECM.

Idle position of throttle valve is determined by the ECM receiving signal from the TPS. TPS controls engine operation such as fuel cut. Wide open and closed throttle position switches, built into TPS unit, are not used for engine control.