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Home >> Lexus >> 2004 >> IS 300 Base, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 9 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P0121: Throttle (TP)/Pedal Position Sensor Switch "A" Circuit Range/Performance Fault >> Circuit Description
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Circuit Description

WARNING: This page is about a different car, the 2002 Lexus RX 300. However, it is still accessible from the selected car via links, so may be relevant.

The TP sensor is a variable resistor that monitors throttle opening. TP sensor is mounted in throttle body. ECM determines vehicle driving condition and adjusts air/fuel mixture accordingly. DTC is set when after vehicle speed has exceeded 19 MPH and output value of TP sensor was out of range with vehicle speeds of 0-19 MPH. Possible cause is; faulty Throttle Position (TP) sensor.

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