P0123: Throttle position sensor circuit high input
Drive carefully. Get it checked within a week or two.
Can I drive with P0123?
Yes, but drive carefully and get it checked soon. The ECU reads wide-open throttle at all times, causing surging, high idle, and harsh gear shifting.
What does P0123 mean?
P0123 stands for Throttle/Pedal Position Sensor/Switch 'A' Circuit High Input.
Symptoms you may notice
- Sudden 'Reduced Engine Power' warning on dashboard
- Gas pedal feels dead or vehicle will not accelerate past 25-30 mph
- Jerky throttle response and abrupt engine surging
How much does it cost to fix?
Repair costs for code P0123 depend on the specific underlying root cause, ranging from simple DIY checks to component replacement. The table below lists the most common causes and rough price ranges in USD:
- Short to reference voltage or battery 12V in signal wire
- Internally failed TPS potentiometer
- Broken sensor ground wire
- Damaged throttle body connector seal
What to do next
- Check whether TPS voltage drops when the sensor is disconnected.
- Inspect the ground circuit of the throttle sensor using a multimeter.
- Inspect wiring harness along the firewall for cuts or melted insulation.
Last updated: October 2026
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General guidance only, not a professional diagnosis. If the check-engine light is flashing, or the car is running rough, overheating or losing power, stop driving and get help.
About this code
Code P0123 triggers when the throttle position circuit exceeds 4.65 volts continuously. The engine computer believes you are constantly flooring the accelerator, which can cause erratic revving at stoplights. Fixing ground faults or replacing the sensor unit restores normal engine throttle response.