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 P0123: Throttle Position Sensor 1 Signal Circuit High Input: General Description
The Electronic Throttle Control (ETC) system consists of the throttle body, Throttle Position Sensor (TPS) 1 & 2 and Accelerator Position Sensor (APS) 1 & 2. TPS 1 & 2 share the same source voltage and ground. The PCM controls the throttle motor to open and close the throttle valve. The TPS1 output voltage increases in proportion with the throttle valve opening after starting. TPS2 output voltage decreases in proportion with the throttle valve opening angle after starting. The TPS provides feedback to the PCM to control the throttle motor in response to the APS.
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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.