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Engine-Codes – GMC – P0643 2016 GMC Sierra

P0643 2016 GMC Sierra Code - 5 Volt Reference 1 Circuit High Voltage

Quick Answer

The P0643 diagnostic trouble code (DTC) for a 2016 GMC Sierra indicates that the 5-volt reference circuit 1 is registering a high voltage. Common causes include Faulty 5-volt reference circuit, Short circuit or open circuit in the wiring harness, Malfunctioning sensor connected to the 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
P0643 2016 GMC Sierra indicates 5 Volt Reference 1 Circuit High Voltage.
Common causes
Common causes include Faulty 5-volt reference circuit, Short circuit or open circuit in the wiring harness, Malfunctioning sensor connected to the 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 17, 2024
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Code P0643 2016 GMC Sierra Description

The P0643 diagnostic trouble code (DTC) for a 2016 GMC Sierra indicates that the 5-volt reference circuit 1 is registering a high voltage. This code is typically triggered when the Engine Control Module (ECM) detects that the voltage on the 5-volt reference circuit is higher than the specified range. The 5-volt reference circuit is crucial for various sensors and components in the vehicle to function properly, as it provides a stable voltage supply for their operation.

OBDII Code P0643 2016 GMC Sierra - 5 Volt Reference 1 Circuit High Voltage
P0643 2016 GMC Sierra Code - 5 Volt Reference 1 Circuit High Voltage

Common Causes of P0643 2016 GMC Sierra

  1. Faulty 5-volt reference circuit
  2. Short circuit or open circuit in the wiring harness
  3. Malfunctioning sensor connected to the circuit
  4. ECM malfunction

Symptoms of P0643 2016 GMC Sierra

  1. Check Engine Light illuminated on the dashboard
  2. Engine may run rough or stall
  3. Decreased fuel efficiency
  4. Loss of power or acceleration
  5. Erratic sensor readings

How to Fix P0643 2016 GMC Sierra

  1. Diagnose the issue by using a scan tool to retrieve the DTC and perform a thorough inspection of the 5-volt reference circuit and related components.
  2. Check the wiring harness for any visible damage, corrosion, or loose connections. Repair or replace as necessary.
  3. Test the sensors connected to the 5-volt reference circuit to determine if they are functioning correctly. Replace any faulty sensors.
  4. If the issue persists, inspect the ECM for any signs of damage or malfunction. Replace the ECM if necessary.
  5. Clear the DTC and perform a test drive to ensure the issue has been resolved.

Cost to Fix P0643 2016 GMC Sierra

The cost of repairing a P0643 code on a 2016 GMC Sierra can vary depending on the specific cause of the issue and the labor rates at the auto repair shop. In general, the parts required for this repair may range from $50 to $200, while the labor costs can range from $100 to $300. Overall, the total repair cost for addressing a 5-volt reference circuit high voltage issue typically falls between $150 and $500. It's important to note that these estimates are rough averages, and actual costs may differ based on factors such as location, vehicle make and model, and the extent of the repairs needed. It's recommended to consult with a qualified mechanic or auto repair shop for a more accurate cost estimate based on your specific situation.

What does this mean?

Tech Notes for P0643 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 P0643 2016 GMC Sierra code?

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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 P0643 2016 GMC Sierra Code

1. What does the OBDII code P0643 mean for a 2016 GMC Sierra?

P0643 indicates a high voltage issue in the 5 Volt Reference 1 circuit, which provides a stable voltage to various sensors in the vehicle.

2. What are the common symptoms of the P0643 code on a 2016 GMC Sierra?

Symptoms can include a check engine light, erratic engine performance, stalling, poor fuel economy, or inoperative sensors.

3. What causes the P0643 code to appear on a 2016 GMC Sierra?

Common causes include a shorted sensor, wiring issues, a faulty PCM (Powertrain Control Module), or a damaged 5-volt reference circuit.

4. Can a faulty sensor trigger the P0643 code?

Yes, a faulty sensor that uses the 5 Volt Reference 1 circuit can cause the voltage to go out of range and trigger the code.

5. How do I diagnose the P0643 code on my 2016 GMC Sierra?

Start by inspecting the wiring and connectors for damage or corrosion, check for shorted sensors on the 5-volt reference circuit, and test the PCM for proper operation.

6. Can I drive with the P0643 code on my 2016 GMC Sierra?

It’s not recommended to drive with this code, as it may affect engine performance and could potentially cause further damage.

7. How much does it cost to fix the P0643 code on a 2016 GMC Sierra?

Repair costs can vary but typically range from $100 to $500 depending on whether the issue is a sensor, wiring, or the PCM.

8. What sensors rely on the 5 Volt Reference 1 circuit in a 2016 GMC Sierra?

Sensors like the throttle position sensor (TPS), manifold absolute pressure (MAP) sensor, and fuel pressure sensor commonly use the 5-volt reference circuit.

9. How can I prevent the P0643 code from recurring?

Regularly inspect and maintain wiring, connectors, and sensors to ensure they remain in good condition and free of corrosion or damage.

10. Do I need to replace the PCM if I get a P0643 code on my 2016 GMC Sierra?

Not necessarily. The PCM should only be replaced if all other potential causes, like wiring and sensors, have been ruled out and the PCM is confirmed to be faulty.

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