Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Aids
After confirming DTC P0120, use Toyota hand-held tester or scan tool to determine throttle valve opening by reading THROTTLE POS (displayed as a percentage) and THROTTLE POS#2 (displayed as a voltage) to determine probable cause. See THROTTLE VALVE OPENING POSITION SPECIFICATIONS table. Using hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.
| Condition & Throttle Position Reading | Probable Cause | |
|---|---|---|
| Accelerator Pedal Released | ||
| Throttle Pos (0%) & Throttle Pos #2 (0 Volts) | Open In VC Circuit | |
| Throttle Pos (0%) & Throttle Pos #2 (2.0-2.9 Volts) | Open Or Short To Ground In VTA Circuit | |
| Throttle Pos (8-20%) & Throttle Pos #2 (0 Volts) | Open Or Short To Ground In VTA2 Circuit | |
| Throttle Pos (100%) & Throttle Pos #2 (5 Volts) | Open In E2 Circuit | |
| Accelerator Pedal Depressed | ||
| Throttle Pos (0%) & Throttle Pos #2 (0 Volts) | Open In VC Circuit | |
| Throttle Pos (0%) & Throttle Pos #2 (4.7-5.1 Volts) | Open Or Short To Ground In VTA Circuit | |
| Throttle Pos (64-96%) & Throttle Pos #2 (0 Volts) | Open Or Short To Ground In VTA2 Circuit | |
| Throttle Pos (100%) & Throttle Pos #2 (5 Volts) | Open In E2 Circuit | |
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.