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P0642 2016 GMC Sierra Code - 5 Volt Reference 1 Circuit Low Voltage

Quick Answer

The P0642 code in a 2016 GMC Sierra indicates a problem with the 5 Volt Reference 1 Circuit, specifically low voltage. Common causes include Damaged wiring or connectors in the 5 Volt Reference Circuit, Faulty ECM, Malfunctioning sensor drawing too much current. 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 2016 GMC Sierra indicates 5 Volt Reference 1 Circuit Low Voltage.
Common causes
Common causes include Damaged wiring or connectors in the 5 Volt Reference Circuit, Faulty ECM, Malfunctioning sensor drawing too much current.
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 15, 2024
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Code P0642 2016 GMC Sierra Description

The P0642 code in a 2016 GMC Sierra indicates a problem with the 5 Volt Reference 1 Circuit, specifically low voltage. The 5 Volt Reference Circuit is a crucial component in the vehicle's electronic system, providing a stable 5-volt power supply to various sensors and components. When the voltage in this circuit drops below the specified range, it can lead to issues with the proper functioning of these sensors and components, affecting the overall performance of the vehicle.

OBDII Code P0642 2016 GMC Sierra - 5 Volt Reference 1 Circuit Low Voltage
P0642 2016 GMC Sierra Code - 5 Volt Reference 1 Circuit Low Voltage

Common Causes of P0642 2016 GMC Sierra

  1. Damaged wiring or connectors in the 5 Volt Reference Circuit
  2. Faulty ECM
  3. Malfunctioning sensor drawing too much current
  4. Short circuit in the system
  5. Corrosion or poor connections in the circuit

Symptoms of P0642 2016 GMC Sierra

  1. Check Engine Light is illuminated
  2. Engine performance issues such as rough idling or stalling
  3. Decreased fuel efficiency
  4. Inaccurate sensor readings
  5. Electrical issues such as flickering lights or erratic behavior of electronic components

How to Fix P0642 2016 GMC Sierra

  1. Begin by conducting a thorough inspection of the wiring and connectors in the 5 Volt Reference Circuit to identify any damage or corrosion. Repair or replace any faulty components.
  2. Test the ECM to determine if it is functioning properly. If necessary, replace the ECM with a new unit.
  3. Check each sensor connected to the 5 Volt Reference Circuit for any malfunctions. Replace any sensors that are drawing too much current.
  4. Clear the diagnostic trouble codes from the vehicle's memory using a scan tool and test drive the vehicle to ensure that the issue has been resolved.
  5. If the problem persists, consult a professional mechanic or dealership for further diagnostics and repairs.

Cost to Fix P0642 2016 GMC Sierra

The typical repair costs for addressing a P0642 code in a 2016 GMC Sierra can vary depending on the specific cause of the issue. In general, the cost of parts such as wiring, connectors, sensors, or an ECM replacement can range from $200 to $800. Labor costs at auto repair shops typically range from $80 to $150 per hour. Additional diagnostic time may also be required to pinpoint the exact cause of the problem. It's advisable to check with local auto repair shops for a more accurate estimate based on your location and vehicle specifics.

What does this mean?

Tech Notes for P0642 2016 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 1 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)



- Air conditioning (A/C) refrigerant pressure sensor

- Camshaft position sensor

- Engine oil pressure sensor

- Fuel pressure sensor

- Fuel rail pressure sensor

- Fuel tank pressure sensor

- Multifunction intake air sensor

Need more information about the P0642 2016 GMC Sierra code?

Need more information on how to fix the P0642 2016 GMC Sierra code? Get Access to Factory Service Manuals

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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 P0642 2016 GMC Sierra Code

1. What does the OBDII code P0642 mean on a 2016 GMC Sierra?

P0642 indicates a low voltage issue in the 5-volt reference 1 circuit, which supplies power to various sensors in the vehicle.

2. What are the common symptoms of code P0642 in a 2016 GMC Sierra?

Symptoms may include poor engine performance, reduced fuel efficiency, illuminated check engine light, and erratic sensor readings.

3. What causes the P0642 code on a 2016 GMC Sierra?

Common causes include a shorted sensor, damaged wiring, a faulty control module, or corrosion in the 5-volt reference circuit.

4. Can I drive my 2016 GMC Sierra with the P0642 code?

Driving with this code is not recommended as it may lead to further damage or unsafe vehicle performance due to incorrect sensor data.

5. How do I diagnose the P0642 code on my GMC Sierra?

Start by scanning the vehicle for additional codes, inspecting the wiring and sensors connected to the 5-volt reference circuit, and testing for proper voltage with a multimeter.

6. Which sensors are typically affected by the P0642 code?

Sensors such as the throttle position sensor (TPS), manifold absolute pressure (MAP) sensor, and coolant temperature sensor may be impacted.

7. Can a bad ground connection cause the P0642 code?

Yes, a poor ground connection can disrupt the 5-volt reference circuit, leading to the P0642 code.

8. How do I fix the P0642 code on a 2016 GMC Sierra?

Repairs may include replacing a shorted sensor, repairing damaged wiring, cleaning corroded connections, or replacing a faulty control module.

9. Does the P0642 code always indicate a sensor failure?

No, while a faulty sensor is a common cause, the issue could also stem from wiring issues or a malfunctioning control module.

10. How much does it cost to repair the P0642 code on a GMC Sierra?

Repair costs vary depending on the root cause, ranging from $50 for minor wiring repairs to $500 or more for control module replacement.

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