AutoCodes – GMC – P0651 GMC

P0651 GMC Code - 5 Volt Reference 2 Circuit

Quick Answer

The Engine Control Module (ECM) has four (4) internal 5 Volt reference circuits (Some models have two (2) internal 5 Volt reference circuits). Common causes include Faulty Sensor on 5 Volt circuit, Sensor on 5 Volt circuit harness is open or shorted, Sensor on 5 Volt circuit poor electrical connection. 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 GMC indicates 5 Volt Reference 2 Circuit.
Common causes: Common causes include Faulty Sensor on 5 Volt circuit, Sensor on 5 Volt circuit harness is open or shorted, Sensor on 5 Volt circuit poor electrical connection.
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.

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Code Popularity 22,602

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jul 17, 2022

Description
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
FAQs
Comments
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Code P0651 GMC Description

The Engine Control Module (ECM) has four (4) internal 5 Volt reference circuits (Some models have two (2) internal 5 Volt reference circuits). Each internal reference circuit provides external 5 Volt reference circuits for more than one sensor. A short to ground or short to voltage on one external 5 Volt reference circuit can affect all the components connected to the same internal 5 Volt reference circuit. The Diagnostic Trouble Code (DTC) will be set when the ECM detects a short to voltage or ground on any of the 5 Volt reference circuits for greater than 0.5 s.

OBDII Code P0651 GMC - 5 Volt Reference 2 Circuit - AutoCodes.com — P0651 GMC Code - 5 Volt Reference 2 Circuit

What does this mean?

What are the Possible Causes of the DTC P0651 GMC?

Faulty Sensor on 5 Volt circuit
Sensor on 5 Volt circuit harness is open or shorted
Sensor on 5 Volt circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P0651 GMC?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

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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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0651 GMC code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P0651 GMC code?

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Need Help with the Code?

Get the P0651 GMC code diagnosed by a professional: Find a repair shop in your area

Information for Specific GMC Models

P0651 2014 GMC Sierra — 5 Volt Reference 2 Circuit
P0651 2015 GMC Sierra — 5 Volt Reference 2 Circuit
P0651 2016 GMC Sierra — 5 Volt Reference 2 Circuit
P0651 2017 GMC Sierra — 5 Volt Reference 2 Circuit
P0651 2018 GMC Sierra — 5 Volt Reference 2 Circuit

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 P0651 GMC Code

1. What are common symptoms of OBDII code P0651 GMC (5 Volt Reference 2 Circuit)?

Common symptoms include engine stalling, rough idling, poor acceleration, and illuminated Check Engine Light.

2. What does the OBDII code P0651 GMC indicate?

The code P0651 indicates a malfunction in the 5 Volt Reference 2 circuit, which is used by various engine sensors.

3. What are possible causes of OBDII code P0651 GMC?

Potential causes include a faulty 5 Volt reference circuit, damaged wiring or connectors, issues with the Engine Control Module (ECM), or a defective sensor.

4. How can I diagnose the cause of OBDII code P0651 GMC?

Diagnosis involves using a digital multimeter to test the voltage in the affected circuit, inspecting wiring and connectors for damage, and checking the sensors connected to the 5 Volt Reference 2 circuit.

5. Can I drive my vehicle with OBDII code P0651 GMC?

It is not recommended to drive your vehicle with this code as it can lead to performance issues and potential engine damage. It's best to address the issue promptly.

6. How can I repair OBDII code P0651 GMC?

Repair options include fixing or replacing damaged wiring and connectors, replacing the faulty sensor, or addressing any issues with the ECM. A professional diagnosis may be necessary.

7. Is it safe to clear the OBDII code P0651 GMC without fixing the issue?

Clearing the code without addressing the underlying problem is not recommended, as it will likely return, and the underlying issue may worsen over time.

8. Can a DIY enthusiast fix OBDII code P0651 GMC?

Depending on your skill level and access to tools, you may be able to address simpler causes like damaged wiring. For more complex issues, consulting a professional is advisable.

9. How much does it cost to repair OBDII code P0651 GMC?

The cost of repair can vary widely depending on the root cause of the issue, the parts needed, and whether you choose to perform the repair yourself or seek professional help.

10. How can I prevent OBDII code P0651 GMC from occurring again?

Regular maintenance, avoiding electrical overloads, and promptly addressing any sensor or wiring issues can help prevent the recurrence of the P0651 trouble code.