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.
DTC P0122: Throttle Position Sensor 1 Signal Circuit Low Input: General Description
The Electronic Throttle Control (ETC) system consists of the throttle body, Throttle Position Sensor (TPS) 1 and 2, and Accelerator Position Sensor (APS) 1 and 2. The same source voltage and ground are shared by TPS 1 and 2. The throttle valve opening is controlled by the throttle motor, which is controlled by the Engine Control Module (ECM). The opposite position indicator shows inverted signal characteristics. The TPS 1 output voltage increases smoothly in proportion with the throttle valve opening angle after starting. The TPS 2 output voltage decreases in inverse proportion with the throttle valve opening angle after starting. The Throttle Position Sensor provides feedback to the ECM in order to control the throttle motor's valve opening angle properly, in response to the current driving condition.
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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.