P0123: Throttle Position Sensor Circuit High Input

What does error code P0123 mean?

The P0123 diagnostic trouble code stands for "Throttle Position Sensor Circuit High Input." This code is triggered when the powertrain control module detects a high voltage signal from the throttle position sensor. The throttle position sensor monitors the throttle valve position and sends data to the powertrain control module to regulate fuel delivery and engine performance. A high voltage reading suggests a malfunction in the sensor or its circuit, leading to improper throttle control.

Why it's important to address this error code

The throttle position sensor is essential for accurate engine performance, fuel efficiency and smooth acceleration. A faulty throttle position sensor signal can cause poor throttle response, unsteady idling or unintended acceleration, making the vehicle unsafe to drive. If ignored, this issue can lead to further engine and transmission problems, reduced fuel economy and potential stalling.

Can I safely drive my car with this error code?

It isn't recommended you drive with this error code. The vehicle may experience erratic throttle responses or unexpected acceleration or even enter limp mode, significantly limiting power. These issues can create dangerous driving conditions because of how unpredictable the throttle pedal can become, especially in traffic or at high speeds. An immediate diagnosis and repair are recommended to restore safe operation.

How do I know I have the P0123 error code?

• Illuminated check engine light

• Erratic throttle response or hesitation

• Engine stalling or rough idling

• Poor fuel economy

• Sudden unintended acceleration

• Vehicle stuck in limp mode with reduced power

How is it diagnosed?

Diagnosing the P0123 code involves several steps:

• Use an OBD-II scanner: Confirm the P0123 code and check for additional related codes.

• Inspect the throttle position sensor: Look for visible damage, loose connections or corrosion.

• Test the throttle position sensor voltage with a multimeter: Measure the sensor’s output voltage to detect irregular readings.

• Check the wiring and connectors: Inspect for damaged, frayed or shorted wires that could cause high voltage signals.

• Verify throttle body function: Ensure smooth throttle plate movement and check for carbon buildup that could interfere with sensor readings.

• Test the powertrain control module: If all other components function correctly, the powertrain control module may be faulty.

How is the P0123 error code repaired?

Repairs for the P0123 code may include:

• Replacing the faulty throttle position sensor.

• Repairing or replacing damaged wiring or connectors.

• Cleaning the throttle body to remove carbon buildup.

• Resetting or reprogramming the powertrain control module if necessary.

• Testing and replacing the powertrain control module if it is determined to be defective.

• Clearing the error code and performing a test drive to ensure proper function.

Related reading

Follow the link below to reach our catalog of diagnostic check engine trouble codes:
On-board diagnostics (OBD-II) trouble code directory