P0123 Code: Throttle Pedal Position Sensor/Switch (TPS) A Circuit High Input

Updated on Feb 19, 2024  •  3 min read

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The P0123 diagnostic trouble code (DTC) is related to a problem with the Throttle Position Sensor (TPS). The TPS is a sensor that measures the position of the throttle valve in the engine and sends this information to the engine control module (ECM). The ECM uses this information to control the fuel injection and ignition timing.

When the ECM detects a voltage signal from the TPS that is higher than the expected range, it sets the P0123 code and illuminates the Check Engine Light (CEL). This can indicate a fault in the TPS circuit or the sensor itself.

Summary

P0123 Code: Indicates a problem with the Throttle Position Sensor (TPS) sending a higher than expected voltage signal.

Causes: Faulty TPS, incorrect ECM readings, or issues with the throttle body assembly.

Symptoms: Engine misfires, reduced power/acceleration, and stalling.

Diagnosis and Fix: Involves checking TPS voltage, testing wiring, and inspecting the sensor for faults.

Prevention: Regular maintenance, checking the TPS, keeping the engine compartment clean, and prompt issue resolution.

What You'll Read About

What Causes a P0123 Code?

  • The TPS is not sending correct information to the ECM.
  • The TPS is faulty.
  • The ECM is faulty, or it’s not receiving correct information from the TPS.
  • The ECM isn’t sending correct information to your throttle body assembly (part of your engine).

Symptoms of a P0123 Code

  • Engine misfires
  • Reduced power and/or acceleration
  • Stalling at stop lights or when coming to a complete stop in traffic

Diagnosing and Fixing a P0123 Code

If you suspect that your vehicle has a P0123 code, it is essential to have a professional mechanic diagnose and repair the issue. The following are some steps that a mechanic may take to diagnose and fix a P0123 code:

  • Checking the TPS voltage: The mechanic may use a multimeter to measure the voltage output of the TPS while the engine is running. If the voltage is not within the expected range, the TPS may need to be replaced.
  • Testing the wiring: The mechanic may also test the wiring between the TPS and the ECM to ensure that there are no breaks or shorts in the circuit. If any issues are found, the wiring may need to be repaired or replaced.
  • Inspecting the sensor: The mechanic may inspect the TPS to ensure that it is working correctly and is not damaged or worn. If the TPS is found to be faulty, it may need to be replaced.

Preventing a P0123 Code

While some factors that contribute to a P0123 code are beyond the driver’s control, there are steps you can take to help prevent this issue from occurring:

  • Regular maintenance: Sticking to a regular maintenance schedule is crucial for the health of your vehicle. A well-maintained vehicle is less likely to experience issues like a faulty TPS, which can lead to a P0123 code.
  • Checking the TPS: It’s a good idea to check the TPS periodically, especially if you notice any symptoms of a potential issue. You can use a multimeter to check the voltage output of the TPS and compare it to the manufacturer’s specifications.
  • Keep the engine compartment clean: Dirt and moisture in the engine compartment can cause problems with the TPS and other sensors. Regularly cleaning the engine compartment can help prevent these issues.
  • Fixing issues promptly: If you notice any symptoms of a potential issue, such as rough idling or decreased power, it’s essential to have the issue diagnosed and repaired promptly. Ignoring these symptoms can lead to more significant problems, including a P0123 code.

By taking these steps, you can help prevent a P0123 code from occurring and keep your vehicle running smoothly. If you do experience a P0123 code, it’s essential to have the issue diagnosed and repaired promptly to ensure the safety and longevity of your vehicle.

Parts: Throttle Position Sensor

The throttle position sensor is a device that measures the position of your throttle pedal and sends that information to your vehicle’s computer. The TP sensor is often referred to as a “TPS,” which stands for Throttle Position Switch.

The TPS operates in conjunction with other components in your engine’s air intake system, including the throttle body, intake manifold, and air filter.

You can purchase throttle position sensor from AutoZone.

Additional information

In order to troubleshoot your car’s problem, you will need to check the codes. This can be done by a certified mechanic or at home with an OBD2 code reader. If you want to do it yourself and save some money, here are the steps:

  • Turn the ignition key to on position (do not start engine).
  • Wait for about two seconds then turn it back off again.
  • Within five seconds of turning off your vehicle’s ignition switch, press down on both brake pedals firmly for at least 5 seconds and release them slowly while still pressing down firmly until all lights shut off completely before releasing pressure from brake pedal(s). This should clear any stored diagnostic trouble codes (DTC) in memory so they won’t show up when testing next time around.

Conclusion

In conclusion, the P0123 diagnostic trouble code is related to a problem with the Throttle Position Sensor (TPS). If you suspect that your vehicle has a P0123 code, it’s essential to have a professional mechanic diagnose and repair the issue as soon as possible to ensure the safety and longevity of your vehicle.