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 P0120 is set when ECM consistently detects less than .1 volt on VTA circuit. DTC P0120 is also set if ECM consistently detects 4.9 volts or more on VTA circuit. Possible causes are:

Open or short in TP sensor circuit.
Faulty TP sensor.
Faulty ECM.

NOTE: If DTCs P0110, P0115 and P0120 are output together, inspect ECM terminal E2 (ground) circuit for an open. Repair as necessary. See WIRING DIAGRAMS article.