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Engine-Codes – GMC – P0651 2018 GMC Sierra

P0651 2018 GMC Sierra Code - 5 Volt Reference 2 Circuit

Quick Answer

The P0651 diagnostic trouble code (DTC) for a 2018 GMC Sierra refers to a 5 Volt Reference 2 Circuit issue. Common causes include Damaged wiring or connectors in the 5 Volt Reference 2 Circuit, Faulty sensor or component receiving the 5-volt reference signal, ECM/PCM malfunction. 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 2018 GMC Sierra indicates 5 Volt Reference 2 Circuit.
Common causes
Common causes include Damaged wiring or connectors in the 5 Volt Reference 2 Circuit, Faulty sensor or component receiving the 5-volt reference signal, ECM/PCM malfunction.
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 14, 2024
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Code P0651 2018 GMC Sierra Description

The P0651 diagnostic trouble code (DTC) for a 2018 GMC Sierra refers to a 5 Volt Reference 2 Circuit issue. In modern vehicles, the Engine Control Module (ECM) or Powertrain Control Module (PCM) sends out 5-volt reference signals to various sensors and components throughout the vehicle. These reference signals are used by these sensors and components to provide crucial data to the ECM/PCM for proper operation and performance.

OBDII Code P0651 2018 GMC Sierra - 5 Volt Reference 2 Circuit
P0651 2018 GMC Sierra Code - 5 Volt Reference 2 Circuit

Common Causes of P0651 2018 GMC Sierra

  1. Damaged wiring or connectors in the 5 Volt Reference 2 Circuit
  2. Faulty sensor or component receiving the 5-volt reference signal
  3. ECM/PCM malfunction
  4. Short circuit in the circuit
  5. Corrosion or poor connections in the circuit

Symptoms of P0651 2018 GMC Sierra

  1. Check Engine Light illuminated on the dashboard
  2. Engine running rough or misfiring
  3. Loss of power or acceleration
  4. Poor fuel economy
  5. Vehicle stalling or difficulty starting

How to Fix P0651 2018 GMC Sierra

  1. Begin by using a diagnostic scanner to retrieve the trouble codes and confirm the presence of the P0651 code.
  2. Inspect the wiring and connectors in the 5 Volt Reference 2 Circuit for any damage, corrosion, or loose connections. Repair or replace as necessary.
  3. Test the sensors or components that receive the 5-volt reference signal to determine if they are functioning correctly. Replace any faulty sensors or components.
  4. Clear the trouble codes from the ECM/PCM memory and test drive the vehicle to ensure the issue has been resolved.
  5. If the problem persists, further diagnostic testing may be required to pinpoint the exact cause of the P0651 code.

Cost to Fix P0651 2018 GMC Sierra

The typical repair costs for addressing a P0651 code on a 2018 GMC Sierra can vary depending on the specific cause of the issue. In general, the cost of parts for this repair can range from $50 to $200, while labor costs can range from $100 to $300. However, it's important to note that these are rough estimates, and actual costs may vary based on factors such as location, vehicle make and model, and the specific repair shop. It's recommended to consult with a qualified mechanic or auto repair shop to get a more accurate cost estimate for resolving the P0651 code.

What does this mean?

Tech Notes for P0651 2018 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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