LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 2004 >> IS 300 Base, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 39 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P0121: Throttle Position (TP) Sensor "A" Circuit Range/Performance Fault >> Circuit Description
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Circuit Description

WARNING: This page is about a different car, the 2002 Lexus SC 430. However, it is still accessible from the selected car via links, so may be relevant.

The TP sensor is a dual variable resistor sensor that monitors throttle opening and TP sensor malfunction. Based on TP sensor signal, ECM determines vehicle driving condition and uses and uses throttle control motor to set throttle angle accordingly. DTC is set after vehicle speed has been exceeded 19 MPH, even once, output value of throttle position sensor is out of applicable range wile vehicle speed is between 0-19 MPH. Possible cause is; faulty TP sensor.