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P2123 2017 GMC Sierra Code - Accelerator Pedal Position Sensor 1 Circuit High Voltage

Quick Answer

The P2123 diagnostic trouble code (DTC) indicates that the Accelerator Pedal Position Sensor 1 circuit in a 2017 GMC Sierra is registering a high voltage signal. Common causes include Faulty Accelerator Pedal Position Sensor, Damaged or corroded wiring and connectors in the circuit, ECM software or hardware issues. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P2123 2017 GMC Sierra indicates Accelerator Pedal Position Sensor 1 Circuit High Voltage.
Common causes
Common causes include Faulty Accelerator Pedal Position Sensor, Damaged or corroded wiring and connectors in the circuit, ECM software or hardware issues.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
What is this?
Table of contents Created and updated by William Orellana on Sep 11, 2024
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Code P2123 2017 GMC Sierra Description

The P2123 diagnostic trouble code (DTC) indicates that the Accelerator Pedal Position Sensor 1 circuit in a 2017 GMC Sierra is registering a high voltage signal. This sensor is responsible for monitoring the position of the accelerator pedal and sending this information to the Engine Control Module (ECM) to adjust the fuel delivery and engine performance accordingly.

OBDII Code P2123 2017 GMC Sierra - Accelerator Pedal Position Sensor 1 Circuit High Voltage
P2123 2017 GMC Sierra Code - Accelerator Pedal Position Sensor 1 Circuit High Voltage

Common Causes of P2123 2017 GMC Sierra

  1. Faulty Accelerator Pedal Position Sensor.
  2. Damaged or corroded wiring and connectors in the circuit.
  3. ECM software or hardware issues.
  4. Loose or poor connections in the sensor circuit.
  5. Environmental factors such as moisture or debris affecting the sensor operation.

Symptoms of P2123 2017 GMC Sierra

  1. Hesitation or lack of response when pressing the accelerator pedal.
  2. Engine surging or fluctuating RPMs.
  3. Rough idling or unstable engine performance.
  4. Reduced power or acceleration.
  5. Illumination of the Check Engine Light.

How to Fix P2123 2017 GMC Sierra

  1. Begin by conducting a thorough diagnosis using a scan tool to retrieve the specific DTCs and pinpoint the exact cause of the high voltage in the Accelerator Pedal Position Sensor 1 circuit.
  2. Inspect the sensor, wiring, and connectors for any visible damage, corrosion, or loose connections. Replace or repair any faulty components as needed.
  3. Test the sensor's output voltage using a multimeter to ensure it is within the manufacturer's specifications. Adjust or replace the sensor if necessary.
  4. Clear the DTCs from the ECM's memory and perform a road test to verify that the issue has been resolved and the symptoms have disappeared.
  5. If the problem persists, further diagnostics may be required to identify any underlying issues with the ECM or other related components.

Cost to Fix P2123 2017 GMC Sierra

The typical repair costs for addressing a P2123 code in a 2017 GMC Sierra can range from $150 to $400, depending on the specific cause of the issue and the required parts and labor. This estimate includes the cost of a new Accelerator Pedal Position Sensor, any necessary wiring repairs, and the labor fees associated with the diagnosis and repair process. It's essential to consider that the actual costs may vary based on the repair shop's rates, the location, and the availability of parts. Additionally, the time required for diagnosis and repair can influence the final cost, so it's advisable to consult with a trusted mechanic for a more accurate estimate.

What does this mean?

Tech Notes for P2123 2017 GMC Sierra









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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P2123 2017 GMC Sierra Code

1. What are the common symptoms of OBDII code P2123 on a 2017 GMC Sierra?

When the accelerator pedal position sensor 1 circuit shows high voltage (P2123), common symptoms may include reduced engine power, sudden acceleration surges, and the vehicle going into "limp mode."

2. What causes the OBDII code P2123 on a 2017 GMC Sierra?

The Accelerator Pedal Position Sensor 1 Circuit High Voltage code (P2123) on a 2017 GMC Sierra is often caused by a faulty accelerator pedal position sensor, damaged wiring or connectors, or issues with the engine control module.

3. How can I diagnose the OBDII code P2123 on my 2017 GMC Sierra?

To diagnose the P2123 code, you can use an OBDII scanner to retrieve the trouble code and then inspect the accelerator pedal position sensor and its wiring for any visible damage. Testing the sensor's voltage output can also help pinpoint the issue.

4. Is it safe to drive my 2017 GMC Sierra with the P2123 code?

It is not recommended to drive your GMC Sierra with the P2123 code present, as it can lead to sudden loss of power or unexpected acceleration, posing a safety risk. It's best to address the issue promptly.

5. Can I repair the OBDII code P2123 on my 2017 GMC Sierra myself?

While it is possible to repair the P2123 code yourself if you have the necessary tools and knowledge, it is recommended to consult a professional mechanic to accurately diagnose and fix the issue with the accelerator pedal position sensor.

6. What are the repair options for fixing the P2123 code on a 2017 GMC Sierra?

Repair options for the P2123 code include replacing the accelerator pedal position sensor, repairing damaged wiring or connectors, or reprogramming the engine control module if necessary.

7. How much does it cost to fix the OBDII code P2123 on a 2017 GMC Sierra?

The cost of fixing the P2123 code on a 2017 GMC Sierra can vary depending on the root cause of the issue, the cost of parts, and labor charges. It's advisable to obtain quotes from different mechanics or repair shops.

8. Will resetting the OBDII code P2123 on my 2017 GMC Sierra make it go away permanently?

Resetting the OBDII code P2123 may temporarily clear the code, but if the underlying issue with the accelerator pedal position sensor is not fixed, the code is likely to reappear. It's essential to address the root cause of the problem.

9. Can extreme weather conditions trigger the OBDII code P2123 on a 2017 GMC Sierra?

Extreme weather conditions can potentially affect the performance of sensors and electrical components in your GMC Sierra, leading to issues like the P2123 code. Ensuring proper insulation and protection for these components is important.

10. Is the Accelerator Pedal Position Sensor 1 Circuit High Voltage code (P2123) a common issue in the 2017 GMC Sierra?

While the P2123 code may not be as common as other OBDII codes, issues with the accelerator pedal position sensor can still occur in the 2017 GMC Sierra, requiring proper diagnosis and repair to ensure optimal vehicle performance.

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