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Home >> Lexus >> 1998 >> SC 400 >> 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 dual variable resistor sensor that monitors throttle opening and TP sensor malfunction. Based on the TP sensor signal, the ECM determines vehicle driving condition and adjusts air/fuel mixture accordingly. DTC is set when VTA and VTA2 circuit voltage on TP sensor is out of range for 2 seconds. Possible cause is: