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Engine-Codes – GMC – P279A 2017 GMC Sierra

P279A 2017 GMC Sierra Code - Four Wheel Drive High Range Performance

Quick Answer

The diagnostic trouble code P279A for a 2017 GMC Sierra refers to "Four Wheel Drive High Range Performance." This code indicates that there is a problem with the performance of the vehicle's four-wheel-drive system when operating in high range mode. Common causes include Faulty transfer case actuator, Malfunctioning four-wheel-drive control module, Broken or worn-out transfer case gears. 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
P279A 2017 GMC Sierra indicates Four Wheel Drive High Range Performance.
Common causes
Common causes include Faulty transfer case actuator, Malfunctioning four-wheel-drive control module, Broken or worn-out transfer case gears.
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 10, 2024
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Code P279A 2017 GMC Sierra Description

The diagnostic trouble code P279A for a 2017 GMC Sierra refers to "Four Wheel Drive High Range Performance." This code indicates that there is a problem with the performance of the vehicle's four-wheel-drive system when operating in high range mode. In a four-wheel-drive system, high range mode is typically used for driving at higher speeds on normal roads or highways, providing better traction and stability.

OBDII Code P279A 2017 GMC Sierra - Four Wheel Drive High Range Performance
P279A 2017 GMC Sierra Code - Four Wheel Drive High Range Performance

Common Causes of P279A 2017 GMC Sierra

  1. Faulty transfer case actuator
  2. Malfunctioning four-wheel-drive control module
  3. Broken or worn-out transfer case gears
  4. Electrical issues in the four-wheel-drive system wiring
  5. Low or contaminated fluid levels in the transfer case

Symptoms of P279A 2017 GMC Sierra

  1. Difficulty engaging or disengaging four-wheel-drive high range mode
  2. Dashboard warning light indicating a problem with the four-wheel-drive system
  3. Unusual noises or vibrations when switching between two-wheel-drive and four-wheel-drive modes
  4. Reduced traction or stability when driving in high range mode

How to Fix P279A 2017 GMC Sierra

  1. Diagnose the specific cause of the issue by using a diagnostic scanner to retrieve the fault codes and perform system tests.
  2. Inspect the transfer case actuator, control module, gears, and wiring for any signs of damage or wear.
  3. Replace any faulty components such as the transfer case actuator, control module, or damaged gears.
  4. Check and refill the transfer case with the correct type and amount of fluid if necessary.
  5. Clear the fault codes and perform a test drive to ensure that the issue has been resolved and the four-wheel-drive system is functioning properly.

Cost to Fix P279A 2017 GMC Sierra

The typical repair costs for addressing a P279A code on a 2017 GMC Sierra can range from $200 to $800, including parts and labor. However, it's important to note that the actual cost can vary depending on the specific cause of the issue, the quality of replacement parts used, and labor rates at the auto repair shop. Additionally, diagnosis time and labor rates can vary based on factors such as location, vehicle make and model, and engine type. It's recommended to consult with a trusted mechanic or auto repair shop to get a more accurate estimate based on your specific situation.

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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 P279A 2017 GMC Sierra Code

1. What does OBDII code P279A mean on a 2017 GMC Sierra?

P279A indicates a "Four Wheel Drive High Range Performance" issue, meaning the vehicle's 4WD system is not performing as expected when in high-range mode.

2. What are common symptoms of code P279A in a 2017 GMC Sierra?

Symptoms include the 4WD system not engaging properly, warning lights on the dashboard like the "Service 4WD" light, reduced traction, or unusual noises from the drivetrain.

3. What causes the P279A code in a 2017 GMC Sierra?

Potential causes include a faulty transfer case motor, damaged wiring or connectors, a malfunctioning 4WD control module, or internal transfer case issues.

4. Can I drive my 2017 GMC Sierra with a P279A code?

While the vehicle may still be drivable in 2WD, it could compromise performance in off-road or slippery conditions. It's best to address the issue promptly.

5. How do I diagnose a P279A code on a 2017 GMC Sierra?

Start by scanning for codes using an OBDII scanner, inspecting the transfer case motor and its wiring, and testing the 4WD control module for proper operation.

6. Can a faulty transfer case motor cause the P279A code?

Yes, a malfunctioning transfer case motor is a common cause of this code, as it is responsible for shifting the vehicle into 4WD high-range mode.

7. How much does it cost to fix a P279A code on a 2017 GMC Sierra?

Repair costs vary but may range from $200 to $1,000 depending on whether the issue is with the transfer case motor, wiring, or other components.

8. Can I reset the P279A code without repairs?

Clearing the code with an OBDII scanner may temporarily remove the warning, but the underlying issue will likely cause the code to return.

9. Does the P279A code indicate a serious problem?

While not immediately dangerous, ignoring the code can lead to further damage to the 4WD system or transfer case, increasing repair costs.

10. What preventive maintenance can help avoid a P279A code?

Regularly inspect and maintain the transfer case, lubricate moving parts, and ensure the 4WD system is used periodically to prevent components from seizing.

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