AutoCodes – Ford – P0642 2009 Ford Fusion

P0642 2009 Ford Fusion Code - Sensor Reference Voltage 'A' Circuit Low

Quick Answer

The control module has 2 internal 5-volt reference buses called "5-volt reference 1" and"5-volt reference 2". Common causes include Faulty Engine Control Module (ECM), ECM harness is open or shorted, ECM 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: P0642 2009 Ford Fusion indicates Sensor Reference Voltage 'A' Circuit Low.
Common causes: Common causes include Faulty Engine Control Module (ECM), ECM harness is open or shorted, ECM 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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 2,557

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 May 01, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P0642 2009 Ford Fusion Description

The control module has 2 internal 5-volt reference buses called "5-volt reference 1" and"5-volt reference 2". Each reference bus provided 5-volt reference circuit for more than one sensor. Therefore, a fault condition on one 5-volt reference circuit will affect the other 5-volt reference circuits connected to the reference bus. The control module monitors the voltage on the 5-volt reference buses.

OBDII Code P0642 2009 Ford Fusion - Sensor Reference Voltage 'A' Circuit Low - AutoCodes.com — P0642 2009 Ford Fusion Code - Sensor Reference Voltage 'A' Circuit Low

What does this mean?

What are the Possible Causes of the DTC P0642 2009 Ford Fusion?

Faulty Engine Control Module (ECM)
ECM harness is open or shorted
ECM circuit poor electrical connection
Shorted sensor on 5 volt circuit

How to Fix the DTC P0642 2009 Ford Fusion?

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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0642 2009 Ford Fusion 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 P0642 2009 Ford Fusion code?

Need more information on how to fix the P0642 2009 Ford Fusion code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0642 2009 Ford Fusion code diagnosed by a professional: Find a repair shop in your area

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 P0642 2009 Ford Fusion Code

1. What are the symptoms of OBDII code P0642 on a 2009 Ford Fusion?

The symptoms of P0642 typically include rough engine performance, reduced fuel efficiency, and the illumination of the Check Engine light on the dashboard.

2. What does the OBDII code P0642 indicate in a 2009 Ford Fusion?

P0642 indicates a potential issue with the Sensor Reference Voltage 'A' Circuit being too low in the vehicle's engine control module.

3. What are the possible causes of the Sensor Reference Voltage 'A' Circuit Low code on a 2009 Ford Fusion?

Common causes of P0642 include a faulty engine control module, damaged wiring or connectors in the circuit, or a malfunctioning sensor causing a voltage drop.

4. How can I diagnose the Sensor Reference Voltage 'A' Circuit Low issue on my 2009 Ford Fusion?

Diagnosing P0642 involves using a multimeter to test the voltage in the affected circuit, checking for damaged wires or connectors, and inspecting the related sensors for proper functioning.

5. Can I continue driving my 2009 Ford Fusion with OBDII code P0642?

It is generally not recommended to continue driving with P0642 present, as it can lead to further engine issues and potential damage if left unresolved for an extended period.

6. How can I repair the Sensor Reference Voltage 'A' Circuit Low problem in my 2009 Ford Fusion?

Repairing P0642 may involve replacing the faulty engine control module, repairing damaged wiring or connectors, or replacing the sensor causing the voltage drop in the circuit.

7. Is it possible to reset the Check Engine light after fixing OBDII code P0642 on a 2009 Ford Fusion?

Yes, once the underlying issue causing P0642 is resolved, the Check Engine light can be reset using an OBDII scanner or by disconnecting the car's battery for a few minutes.

8. Are there any common DIY fixes for resolving OBDII code P0642 on a 2009 Ford Fusion?

While some basic troubleshooting steps can be taken, resolving P0642 often requires professional diagnostic equipment and expertise due to the complexity of the engine control system.

9. How much does it typically cost to repair OBDII code P0642 on a 2009 Ford Fusion?

The cost of repairing P0642 can vary depending on the specific cause of the issue, but it may range from a few hundred to over a thousand dollars, including parts and labor.

10. Can OBDII code P0642 on a 2009 Ford Fusion cause permanent damage if not addressed promptly?

If left unresolved, P0642 can potentially lead to more severe engine problems and increased repair costs over time, making it important to address the issue promptly.