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Engine-Codes – Generic – P0651

P0651 Code - Sensor Reference Voltage 'B' Circuit/Open

Quick Answer

The P0651 diagnostic trouble code (DTC) indicates a problem with the sensor reference voltage 'B' circuit being open or disconnected. Common causes include Faulty sensor reference voltage regulator, Wiring or connection issues in the sensor reference voltage circuit, Corrosion or damage to the sensor reference voltage circuit. 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 indicates Sensor Reference Voltage 'B' Circuit/Open.
Common causes
Common causes include Faulty sensor reference voltage regulator, Wiring or connection issues in the sensor reference voltage circuit, Corrosion or damage to the sensor reference voltage circuit.
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 05, 2024
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Code P0651 Description

The P0651 diagnostic trouble code (DTC) indicates a problem with the sensor reference voltage 'B' circuit being open or disconnected. This sensor reference voltage is crucial for providing power to various sensors in the vehicle, allowing them to function properly and provide accurate data to the engine control module (ECM) or powertrain control module (PCM). When this circuit is open, it can lead to issues with sensor operation and data transmission, ultimately affecting the vehicle's performance and efficiency.

OBDII Code P0651 - Sensor Reference Voltage 'B' Circuit/Open
P0651 Code - Sensor Reference Voltage 'B' Circuit/Open

Common Causes of P0651

  1. Faulty sensor reference voltage regulator
  2. Wiring or connection issues in the sensor reference voltage circuit
  3. Corrosion or damage to the sensor reference voltage circuit
  4. ECM or PCM malfunction
  5. Sensor failure impacting the reference voltage circuit

Symptoms of P0651

  1. Check engine light illuminated on the dashboard
  2. Reduced engine performance or power
  3. Inaccurate or erratic sensor readings
  4. Difficulty starting the vehicle
  5. Poor fuel efficiency

How to Fix P0651

  1. Begin by using a diagnostic scanner to retrieve the specific trouble code and confirm the issue.
  2. Inspect the sensor reference voltage circuit for any loose connections, damaged wiring, or corrosion.
  3. Test the sensor reference voltage regulator for proper functioning and replace if necessary.
  4. Check the ECM or PCM for any faults or malfunctions that may be impacting the sensor reference voltage circuit.
  5. Clear the trouble code, reset the ECM/PCM, and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0651

The typical repair costs for addressing a P0651 code can range from $100 to $300, depending on the specific cause of the issue and the parts or components that need to be replaced. Labor rates at auto repair shops can vary, with hourly rates typically falling between $80 and $150. It's recommended to consult with a professional mechanic or shop to get an accurate estimate based on your vehicle's make and model, as well as the local market rates.

When is the Code Detected?

The Engine Control Module (ECM) has detected the sensor 5 volt reference circuit voltage is higher or lower than expected

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Code P0651 Information for Specific Makes

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 Code

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