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Home >> Lexus >> 1998 >> ES 300 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Diagnostic Tests >> DTC P0121: Throttle Position (TP) Sensor Circuit Range/Performance Problem >> Circuit Description
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Circuit Description

The TP sensor is a variable resistor that monitors throttle opening. TP sensor is mounted in throttle body. The 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 at vehicle speeds of 0-19 MPH. Possible cause is: