What are the Symptoms and Causes of P0123 Code? | How to Fix P0123 Code?

The engine consists of multiple parts and sensors. Whenever any of these sensors go bad, your powertrain control module (PCM) triggers a code. Your Throttle Position (TP) sensor plays a vital role to ensure the efficient working of the engine. As your PCM detects a problem with the signal coming from the TP sensor, it triggers the P0123 code. This article deeply explains the P0123 code, meaning symptoms and causes.  

P0123 Code Definition

P0123 trouble code stands for “Throttle Position Sensor/Switch A Circuit High Input.”

What does the P0123 Code Mean?

The P0123 code indicates that the powertrain control module (PCM) received a high input signal than expected from the throttle position sensor A.

P0123 Code

The throttle position (TP) sensor “A” is a potentiometer that is installed on the throttle body and shaft that measures the position of the throttle valve.

 The TP sensor is a device that helps the PCM to regulate the optimal fuel injection and ignition spark timing.

It performs this job by measuring how far the butterfly valve in the throttle body is open and how much air to draw into the intake manifold. The cars with an Electronic Throttle Control (ETC) have two throttle position sensors as a fail-safe measure.

When the PCM of your vehicle gets a signal from the throttle position sensor that exceeds the maximum limit for a specific period, it sets the trouble code P0123.

Specifically, cars with ETC use the accelerator pedal position (APP) sensor to determine the amount of accelerator pedal pressure. Your PCM may also trigger the code P0123 if there is an issue with the pedal position sensor instead of the throttle body sensor.

Causes of the P0123 Code

  • Damaged or contaminated throttle body
  • A bad throttle position sensor
  • Loose or damaged connections
  • A bad pedal position sensor
  • Loose or improperly aligned TP sensor
  • Carbon-fouled throttle body
  • Bad or damaged wiring 
  • Circuit shorted to voltage
  • PCM issues (e.g., the software update is required)

Symptoms of P0123 Code

  • Check Engine Light illumination
  • Rough idle
  • The engine is in failsafe mode, with the decreased throttle
  • Intermittent stalling
  • Erratic Idle
  • Acceleration problems

Read More: P0102 Code Symptoms and Causes

How to Diagnose the P0123 Code

You need the following tools to diagnose or fix the P0123 code:

  • Electrical Cleaner
  • Auto Repair Manual
  • Diagnostic OBD Scan Tool
  • Throttle body cleaner
  • Basic Hand Tools
  • Multimeter

Follow the below-given steps to diagnose the P0123 code:

  1. Use an OBD-II scanner to scan the trouble code. Check the freeze frame data to examine the condition of your vehicle. Clear any trouble codes and test the vehicle again to see what comes back.
  2. Remove carbon deposits from the throttle body using a special cleaner.
  3. Properly inspect the connectors and wirings of the TP sensor for damage, corrosion, or short. Damaged wiring usually generates different issues, so it’s probably nothing more than a bad connection.
  4. Repair or replace the damaged connection or wiring, but continue to check the scanner data to ensure the fault has been fully resolved.
  5. Relate the data between TP sensor A and B circuits on the scanner. If differences between data points are found, perform the TP sensor accuracy test as suggested by the car manufacturer.
  6. Replace your damaged TP sensor if necessary and clear codes.

 Common P0123 Code Diagnosis Mistakes

  • Replacing the throttle position sensor without inspecting the wiring and connections
  • The TP sensor A and B circuits’ voltages are not tested to requirements before and after the replacement or repair.
  • No visual inspection of the wirings and connections first
  • Changing the TP sensor without confirming that it is the cause of the issue
  • Not scanning, recording, and erasing the codes, then try again to see the cause of failure.

What repairs can fix the P0123 Code?

  • Replacing or fixing the TP sensor connectors for shorting
  • Repairing or replacing the damaged wirings
  • Replacing or cleaning the throttle body
  • Replacing the throttle position sensor 
  • Repairing or reprograming the PCM

Repair Cost of P0123 Code

The repair or fixing cost of the P0123 code varies according to the vehicle model, labor cost, and repair cost of the relevant part. To fix or repair the P0123 code, you may need one or more of the following repairs:

Wiring short repair$20 to $510
TP sensor connector replacement$20 to $80
TP sensor replacement$90 to $320
Throttle body replacement $15 to $670

FAQ Section

How serious is the code P0123?

When P0123 occurs, the powertrain control module of your vehicle will go into the failsafe mode to prevent your vehicle’s transmission system and engine from being damaged.

The failsafe mode leads to various drive problems until the repair is complete. According to the manufacturer’s failsafe policy, drivability problems may include stalling, poor engine performance, speed limitation, bucking or jerking, high idle, or lack of acceleration.

How to reset the throttle position sensor?

The best method to reset the TP sensor is to disconnect the negative battery cable for approximately 5 minutes or remove the fuse for the PCM.

Can I drive with a faulty throttle position sensor?

Yes, you can drive with a faulty throttle position sensor. However, driving with a faulty throttle position sensor is not recommended. This is because you may have multiple issues, including choppy or slow idle, poor engine performance, poor fuel economy, or lack of acceleration.

Can I drive with a P0123 Code?

Yes, you can drive with DTC P0123. However, it is recommended to fix this code as soon as possible because it may create multiple drivability issues. When this code appears, your PCM shifts your car engine into failsafe mode. Due to this mode, you may face different problems, including poor acceleration, lack of engine power, higher fuel consumption, rough idle, or engine stalling.

What happens when your throttle position sensor goes out?

As the throttle position sensor goes bad, you may face one of the below-given problems:

  • Check engine light illumination
  • An unexpected jerking and bucking driving.
  • A sudden increase in speed while moving on the highway.
  • Poor fuel economy
  • Sudden idle surges
  • Poor engine performance
  • Sudden engine stalling
  • Acceleration problems

How do I reset my electronic throttle control manually?

Make sure that the accelerator pedal is fully released and follow the below-given steps;

  1. Turn the ignition switch “ON
  2. Wait up to two seconds. 
  3. Turn the ignition switch “OFF” and wait a minimum of ten seconds. 
  4. Turn the ignition switch “ON” and wait a minimum of two seconds.
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