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P279B 2016 GMC Sierra Code - Four Wheel Drive Low Range Performance

Quick Answer

The diagnostic trouble code P279B for a 2016 GMC Sierra indicates a problem with the performance of the Four Wheel Drive (4WD) Low Range system. Common causes include Faulty 4WD control module, Malfunctioning transfer case actuator, Wiring issues or electrical faults. 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
P279B 2016 GMC Sierra indicates Four Wheel Drive Low Range Performance .
Common causes
Common causes include Faulty 4WD control module, Malfunctioning transfer case actuator, Wiring issues or electrical faults.
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 16, 2024
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Code P279B 2016 GMC Sierra Description

The diagnostic trouble code P279B for a 2016 GMC Sierra indicates a problem with the performance of the Four Wheel Drive (4WD) Low Range system. This system allows the vehicle to operate in low-speed, high-torque situations such as off-road driving or towing heavy loads. When this code is triggered, it means that the control module has detected a discrepancy in the expected performance of the 4WD Low Range system.

OBDII Code P279B 2016 GMC Sierra - Four Wheel Drive Low Range Performance
P279B 2016 GMC Sierra Code - Four Wheel Drive Low Range Performance

Common Causes of P279B 2016 GMC Sierra

  1. Faulty 4WD control module
  2. Malfunctioning transfer case actuator
  3. Wiring issues or electrical faults
  4. Sensor failures related to the 4WD system
  5. Mechanical problems within the transfer case or drivetrain components

Symptoms of P279B 2016 GMC Sierra

  1. Difficulty engaging or disengaging 4WD Low Range mode
  2. Illumination of the 4WD warning light on the dashboard
  3. Unusual noises coming from the transfer case or drivetrain
  4. Reduced traction or control in off-road or low-speed situations

How to Fix P279B 2016 GMC Sierra

  1. Begin by conducting a thorough diagnostic scan to confirm the P279B code and identify the specific cause of the issue.
  2. Inspect the wiring harness and connectors related to the 4WD system for any signs of damage or corrosion.
  3. Test the transfer case actuator and 4WD control module for proper functionality and replace if necessary.
  4. Clear the trouble code from the vehicle's computer system after completing the repair to reset the 4WD Low Range system.
  5. Test drive the vehicle to ensure that the 4WD Low Range system operates correctly and that the symptoms associated with the code have been resolved.

Cost to Fix P279B 2016 GMC Sierra

The typical repair costs for addressing the Four Wheel Drive Low Range Performance issue can vary depending on the specific cause of the problem. In general, parts and labor for this type of repair could range from $200 to $800. However, it's important to note that diagnosis time and labor rates at auto repair shops can vary significantly based on factors such as location, vehicle make and model, and engine type. It's recommended to check with local shops for more accurate estimates. Most auto repair shops charge between $80 and $150 per hour for labor, but rates may be higher at dealerships or in metropolitan areas. Independent shops often offer lower labor rates.

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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 P279B 2016 GMC Sierra Code

1. What does the OBDII code P279B mean on a 2016 GMC Sierra?

The P279B code indicates a performance issue with the Four-Wheel Drive (4WD) Low Range system, meaning the vehicle's computer has detected that the 4WD Low Range is not engaging or operating as expected.

2. What are the common symptoms of a P279B code on a 2016 GMC Sierra?

Symptoms may include the 4WD Low not engaging, a 4WD warning light on the dashboard, reduced off-road capability, or difficulty in transitioning between 4WD modes.

3. What causes the P279B code to appear on a 2016 GMC Sierra?

Common causes include a malfunctioning transfer case motor, faulty 4WD control module, wiring or electrical issues, or mechanical problems within the transfer case.

4. Can I still drive my 2016 GMC Sierra with a P279B code?

Yes, but the 4WD Low function may not work, which could limit performance in off-road or low-traction conditions. It's advisable to address the issue promptly to avoid further damage.

5. How do I diagnose the P279B code on a 2016 GMC Sierra?

Diagnosis involves checking for stored codes, inspecting the transfer case motor and wiring, testing the 4WD control module, and verifying the mechanical integrity of the transfer case.

6. How can I fix the P279B code on my 2016 GMC Sierra?

Repairs may include replacing the transfer case motor, repairing damaged wiring, reprogramming or replacing the 4WD control module, or servicing the transfer case.

7. What tools are needed to troubleshoot a P279B code on a GMC Sierra?

You'll need an OBDII scanner, a multimeter for electrical testing, and possibly specialty tools for accessing and removing the transfer case motor.

8. How much does it cost to repair a P279B code on a 2016 GMC Sierra?

Repair costs vary, but replacing a transfer case motor typically ranges from $500 to $1,200, depending on labor rates and parts pricing.

9. Can low transfer case fluid cause the P279B code on a GMC Sierra?

Yes, insufficient or contaminated transfer case fluid can cause mechanical issues that trigger the P279B code. Checking and replacing the fluid may help resolve the issue.

10. Does the P279B code require a software update on a 2016 GMC Sierra?

In some cases, a software update for the 4WD control module may resolve the issue. Check with your dealership or repair technician for the latest updates.

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