General Information

Engine Control
P0121 Throttle/Pedal Position Sensor/Switch \'A\' Circuit Range/Performance - General Information

Component Location





General Description

The Electronic Throttle Control(ETC) system which is composed of throttle body, Throttle Position Sensor(TPS)1&2 and Accelerator Position Sensor(APS) 1&2 controls the mass of airflow by driver's intention. The throttle valve opening is control by throttle motor which is controlled by ECM. TPS is a variable resistance and its value is cahnged by open angle of throttle valve.

DTC Description

ECM sends DTC P0121 if the difference between the throttle valve position value calculated by TPS1and the designated value by ECM is over certain value when the TPS2 is abnormal.

DTC Detecting Condition





Diagnostic Circuit Diagram










Signal Waveform & Data




Fig.1) Normal waveform of TPS1 & TPS2 with no accel padal depressed under IG ON condition