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Home >> Lexus >> 2004 >> GS 430 >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine (3UZ-FE) - Diagnostics >> Circuit Inspection >> DTC P0121: Throttle/Pedal Position Sensor/Switch "A" Circuit Range/Performance Problem >> Monitor Description

Monitor Description

The ECM uses throttle position sensor to monitor the throttle valve opening angle.

This sensor includes two signals, VTA1 and VTA2. VTA1 is used to detect the throttle opening angle and VTA2 is used to detect malfunctions in VTA1. There are several checks that the ECM confirms proper operation of the throttle position sensor and VTA1.

There is an expected specific voltage difference between VTA1 and VTA2 for each throttle opening angle. If the voltage output difference of the VTA1 and VTA2 deviates from the normal operating range, the ECM interprets this as a malfunction of the throttle position sensor. The ECM will turn on the MIL and a DTC is set.