AutoCodes – Buick – P0651 Buick

P0651 Buick 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 Buick 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 799

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

What does this mean?

What are the Possible Causes of the DTC P0651 Buick?

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 Buick?

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

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0651 Buick 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.

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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 P0651 Buick Code

1. What are the common symptoms of OBDII code P0651 in a Buick related to the 5 Volt Reference 2 Circuit?

- Common symptoms may include engine stalling, rough idling, difficulty starting the vehicle, and issues with engine performance.

2. What are the possible causes of OBDII code P0651 in a Buick indicating a problem with the 5 Volt Reference 2 Circuit?

- Potential causes include a faulty 5 volt reference circuit, a defective Engine Control Module (ECM), damaged wiring or connectors, or a short circuit in the circuit.

3. How can I diagnose the OBDII code P0651 in my Buick related to the 5 Volt Reference 2 Circuit?

- Diagnosis involves using a multimeter to test the 5 volt reference circuit for continuity, checking the wiring and connectors for damage, and inspecting the ECM for any signs of malfunction.

4. Can I still drive my Buick with OBDII code P0651 indicating a problem with the 5 Volt Reference 2 Circuit?

- It is not recommended to drive the vehicle with this code present, as it can lead to potential engine issues and further damage if left unresolved.

5. What are the repair options for fixing OBDII code P0651 in a Buick due to a fault in the 5 Volt Reference 2 Circuit?

- Repair options include repairing or replacing damaged wiring, connectors, or components in the 5 volt reference circuit, and resetting the trouble code with a scan tool after the repair.

6. Can a DIY enthusiast fix OBDII code P0651 in a Buick related to the 5 Volt Reference 2 Circuit?

- While some basic troubleshooting like checking for loose connections can be done by a DIYer, diagnosing and repairing the specific issue causing the code may require professional assistance due to the complexity of the electrical system.

7. Is it safe to reset the OBDII code P0651 in a Buick without fixing the underlying issue with the 5 Volt Reference 2 Circuit?

- It is not recommended to clear the code without addressing the root cause, as the issue may persist and potentially worsen over time, leading to further complications.

8. How long does it typically take to repair OBDII code P0651 in a Buick related to the 5 Volt Reference 2 Circuit?

- The repair time can vary depending on the exact cause of the issue. Simple fixes like repairing a loose connection may take a short time, while more complex issues could require several hours or more.

9. Are there any preventive measures to avoid encountering OBDII code P0651 in a Buick due to problems with the 5 Volt Reference 2 Circuit?

- Regularly inspecting the electrical system, ensuring proper maintenance of the vehicle, and addressing any warning signs promptly can help prevent issues leading to this trouble code.

10. Can extreme weather conditions impact OBDII code P0651 in a Buick related to the 5 Volt Reference 2 Circuit?

- Extreme temperatures or weather conditions may exacerbate existing electrical issues, potentially triggering the code. Keeping the vehicle protected and well-maintained can help mitigate such risks.