Engine-CodesGMC – P0651 2015 GMC Sierra

P0651 2015 GMC Sierra Code - 5 Volt Reference 2 Circuit

Quick Answer

The P0651 code for a 2015 GMC Sierra indicates a problem with the 5 Volt Reference 2 Circuit. Common causes include Faulty ECM: A malfunctioning Engine Control Module can disrupt the 5-volt reference circuit and trigger the P0651 code, Damaged Wiring or Connectors: Corrosion, fraying, or breaks in the wiring or connectors connected to the 5-volt reference circuit can cause voltage irregularities, Short Circuit: A short circuit in the 5-volt reference circuit can lead to voltage spikes or drops that trigger the code. 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
P0651 2015 GMC Sierra indicates 5 Volt Reference 2 Circuit.
Common causes
Common causes include Faulty ECM: A malfunctioning Engine Control Module can disrupt the 5-volt reference circuit and trigger the P0651 code, Damaged Wiring or Connectors: Corrosion, fraying, or breaks in the wiring or connectors connected to the 5-volt reference circuit can cause voltage irregularities, Short Circuit: A short circuit in the 5-volt reference circuit can lead to voltage spikes or drops that trigger the code.
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.
Table of contents Created and updated by William Orellana on Sep 12, 2024
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Code P0651 2015 GMC Sierra Description

The P0651 code for a 2015 GMC Sierra indicates a problem with the 5 Volt Reference 2 Circuit. This code is typically triggered when the Engine Control Module (ECM) detects a voltage signal that is out of the normal range for the 5-volt reference circuit. The 5-volt reference circuit is an essential part of the vehicle's electrical system, providing a stable voltage supply to various sensors and components that require a consistent power source for operation.

OBDII Code P0651 2015 GMC Sierra - 5 Volt Reference 2 Circuit
P0651 2015 GMC Sierra Code - 5 Volt Reference 2 Circuit

Common Causes of P0651 2015 GMC Sierra

  1. Faulty ECM: A malfunctioning Engine Control Module can disrupt the 5-volt reference circuit and trigger the P0651 code.
  2. Damaged Wiring or Connectors: Corrosion, fraying, or breaks in the wiring or connectors connected to the 5-volt reference circuit can cause voltage irregularities.
  3. Short Circuit: A short circuit in the 5-volt reference circuit can lead to voltage spikes or drops that trigger the code.
  4. Failed Sensor or Component: A faulty sensor or component that relies on the 5-volt reference circuit may cause voltage issues and trigger the code.

Symptoms of P0651 2015 GMC Sierra

  1. Check Engine Light: The most common symptom associated with the P0651 code is the illumination of the Check Engine Light on the vehicle's dashboard.
  2. Engine Performance Issues: The vehicle may experience rough idling, stalling, or hesitation during acceleration due to inaccurate sensor readings.
  3. Poor Fuel Efficiency: A faulty 5-volt reference circuit can lead to incorrect fuel delivery, resulting in decreased fuel efficiency.
  4. Emission Control Problems: The vehicle may fail emissions tests or produce higher emissions than normal due to incorrect sensor data.
  5. Electrical Issues: Other electrical components in the vehicle may malfunction or behave erratically if the 5-volt reference circuit is compromised.

How to Fix P0651 2015 GMC Sierra

  1. Diagnose the Issue: Use a diagnostic scanner to retrieve the trouble code and perform a thorough inspection of the 5-volt reference circuit, ECM, wiring, and sensors to pinpoint the cause of the problem.
  2. Repair or Replace Wiring and Connectors: Repair any damaged wiring or connectors in the 5-volt reference circuit to ensure a stable voltage supply.
  3. Test and Replace Sensors or Components: Test the sensors and components connected to the 5-volt reference circuit to identify any faulty ones and replace them as needed.
  4. Reset the ECM: Clear the trouble code from the ECM's memory and reset the system to see if the issue has been resolved.
  5. Perform a Road Test: After the repair, take the vehicle for a test drive to ensure that the P0651 code does not reappear and that the vehicle's performance has been restored.

Cost to Fix P0651 2015 GMC Sierra

The typical repair costs for addressing a P0651 code on a 2015 GMC Sierra can vary depending on the specific cause of the issue. In general, the cost of parts for repairing or replacing wiring, connectors, sensors, or the ECM can range from $100 to $500. Labor costs at auto repair shops typically range from $80 to $150 per hour, with the total repair bill potentially amounting to $200 to $800 or more. However, it's important to note that these estimates are rough figures, and actual costs may vary based on factors such as location, vehicle make and model, and the extent of the repair needed. It's advisable to consult with a professional mechanic or auto repair shop to get a more accurate cost estimate for addressing the P0651 code on a 2015 GMC Sierra.

Tech Notes for P0651 2015 GMC Sierra

Disconnecting one component at a time from the affected 5 Volt reference circuit while observing the scan tool 5 Volt Reference Circuit Status parameter may help locate the fault. The scan tool parameter will change from Malfunction to OK when the source of the fault is disconnected. If all 5 Volt reference components have been disconnected and a fault is still indicated, the fault may exist in the wiring harness.



The 5 Volt reference 2 circuit provides 5 Volt to the following sensors: (Some models may have different sensors, please consult the factory service manual for the list of sensors for your model and year)



- Brake pedal position sensor

- Crankshaft position sensor

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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.

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