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

Quick Answer

The P2123 diagnostic trouble code for GMC vehicles indicates a problem with the Accelerator Pedal Position Sensor 1 Circuit High Voltage. Common causes include Faulty Accelerator Pedal Position Sensor, Corroded or damaged wiring/connectors related to the sensor, Issues with the electronic throttle control system. 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 GMC indicates Accelerator Pedal Position Sensor 1 Circuit High Voltage.
Common causes
Common causes include Faulty Accelerator Pedal Position Sensor, Corroded or damaged wiring/connectors related to the sensor, Issues with the electronic throttle control system.
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 09, 2024
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Code P2123 GMC Description

The P2123 diagnostic trouble code for GMC vehicles indicates a problem with the Accelerator Pedal Position Sensor 1 Circuit High Voltage. This sensor is a crucial component of the vehicle's electronic throttle control system, responsible for sending signals to the engine control module (ECM) regarding the position of the accelerator pedal. The ECM uses this information to adjust the throttle opening and fuel delivery to meet the driver's demands.

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

Common Causes of P2123 GMC

  1. Faulty Accelerator Pedal Position Sensor
  2. Corroded or damaged wiring/connectors related to the sensor
  3. Issues with the electronic throttle control system
  4. Malfunctioning Engine Control Module (ECM)
  5. Electrical interference or short circuits

Symptoms of P2123 GMC

  1. Reduced engine power
  2. Check Engine Light illuminated
  3. Acceleration hesitation
  4. Rough idling
  5. Stalling of the vehicle

How to Fix P2123 GMC

  1. Diagnose the issue by using a scan tool to retrieve the trouble code and assess the sensor's voltage readings.
  2. Inspect the wiring and connectors associated with the Accelerator Pedal Position Sensor for any signs of damage or corrosion.
  3. Test the sensor's resistance and voltage output to determine if it is functioning correctly.
  4. If the sensor is faulty, replace it with a new one following the manufacturer's specifications.
  5. Clear the trouble code from the ECM's memory and perform a test drive to ensure the issue has been resolved.

Cost to Fix P2123 GMC

The cost of repairing a P2123 code for the Accelerator Pedal Position Sensor 1 Circuit High Voltage can vary depending on the extent of the issue and the specific components that need to be replaced. Typically, the cost of a new Accelerator Pedal Position Sensor can range from $50 to $150, while labor costs may range from $100 to $200. Therefore, the total repair cost could be between $150 and $350. It's important to note that these are rough estimates, and actual costs may vary based on the vehicle's make and model, as well as the labor rates charged by auto repair shops in different locations. It's recommended to consult with a professional mechanic for a more accurate cost estimate.

What does this mean?

Tech Notes for P2123 GMC









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Information for Specific GMC Models

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 GMC Code

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  • What model and year is your vehicle? what would you like to reset?

    Reply to Comment

  • Here is the information from the factory service manual:

    Description.
    The Engine Control module (ECM) learns the idle position of the throttle body to ensure the correct idle operation. Anytime the ECM or the throttle body is replaced, the ECM must learn the idle position. The Engine idle may be unstable or a DTC may set if the idle position is not learned.

    Conditions for running the idle learn procedure:
    DTCs P0121, P0122, P0123, P0221, P0222, P0223, P0638, P2100, P2101, P2105, P2107, and P2119 are not set.

    the Engine speed is less than 40 RPM.
    the vehicle speed is 0 KM/h (0 MPH).
    the accelerator pedal position is less than 14.9 percent.
    the ignition 1 voltage is more than 10 volts.
    the Engine coolant temperature is between 5-85°c (41-185°f).
    the intake air temperature is between 5-60°c (41-140°f). Idle learn procedure

    Important:
    ensure the above conditions are MET before proceeding with this procedure.

    do not perform this procedure if a throttle position (TP) sensor or other throttle actuator Control (TAC) system DTCs are set other than P2176. The ECM will not perform the idle learn procedure with a DTC set.

    Turn off the ignition for 30 seconds.
    Turn on the ignition, with the Engine off for 60 seconds.
    Turn off the ignition.
    Turn on the ignition, with the Engine off.

    Clear the DTCs with a scan tool.

    Reply to Comment