AutoCodes – Chevrolet – P279A 2018 Chevrolet Silverado

P279A 2018 Chevrolet Silverado Code - Four Wheel Drive High Range Performance

Quick Answer

The Engine Control Module (ECM) uses the following two ways to determine if the transfer case is in 4WD Low, 4WD High, or Neutral. Common causes include Reprogram Engine Control Module (ECM), Faulty Engine Control Module, Engine Control Module harness is open or shorted. 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 2018 Chevrolet Silverado indicates Four Wheel Drive High Range Performance.
Common causes: Common causes include Reprogram Engine Control Module (ECM), Faulty Engine Control Module, Engine Control Module harness is open or shorted.
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.

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Code Popularity 335

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 Aug 29, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P279A 2018 Chevrolet Silverado Description

The Engine Control Module (ECM) uses the following two ways to determine if the transfer case is in 4WD Low, 4WD High, or Neutral.
1. The first way is to compare the transmission output speed sensor to the transfer case output speed sensor in order to calculate the transfer case range.
2. The second way is to use a LAN message sent by the transfer case shift control module to the ECM.
The ECM uses this message to determine motor torque required and transmission shifting.
The internal fault detection is handled inside the control module. No external circuit diagnosis is involved.
If the first way and second way of determining transfer case range do not match while in 4WD Low, 4WD High or Neutral, then the Diagnostic Trouble Code (DTC) is set.

OBDII Code P279A 2018 Chevrolet Silverado - Four Wheel Drive High Range Performance - AutoCodes.com — P279A 2018 Chevrolet Silverado Code - Four Wheel Drive High Range Performance

What does this mean?

What are the Possible Causes of the DTC P279A 2018 Chevrolet Silverado?

Reprogram Engine Control Module (ECM)
Faulty Engine Control Module
Engine Control Module harness is open or shorted
Engine Control Module circuit poor electrical connection
Transmission internal mechanical problems

How to Fix the DTC P279A 2018 Chevrolet Silverado?

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 P279A 2018 Chevrolet Silverado 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 P279A 2018 Chevrolet Silverado 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 P279A 2018 Chevrolet Silverado Code

1. What are the common symptoms of OBDII code P279A in a 2018 Chevrolet Silverado related to Four Wheel Drive High Range Performance?

The common symptoms include difficulty engaging or disengaging four-wheel drive high range mode, erratic shifting between two-wheel drive and four-wheel drive, and a warning light on the dashboard indicating an issue with the four-wheel drive system.

2. What are the possible causes of OBDII code P279A in a 2018 Chevrolet Silverado?

Possible causes include a malfunctioning transfer case shift control module, damaged wiring or connectors in the four-wheel drive system, low or contaminated transfer case fluid, or a faulty transfer case actuator.

3. How can I diagnose the OBDII code P279A in my 2018 Chevrolet Silverado?

Diagnosing this code involves using a professional OBDII scanner to retrieve the specific fault codes related to the four-wheel drive system, conducting a visual inspection of the wiring and connectors, checking the transfer case fluid level and condition, and testing the transfer case actuator and shift control module for proper functionality.

4. Can I continue to drive my 2018 Chevrolet Silverado with OBDII code P279A present?

It is not recommended to continue driving with this code present, as it may lead to further damage to the four-wheel drive system and potentially result in a loss of control or drivability issues. It is best to address the issue promptly to avoid more significant problems.

5. What are some repair tips for fixing OBDII code P279A in a 2018 Chevrolet Silverado?

Repair tips include checking and replacing any damaged wiring or connectors, ensuring the transfer case fluid is at the correct level and free from contamination, replacing the transfer case actuator if faulty, and reprogramming or replacing the transfer case shift control module as needed.

6. How much does it typically cost to repair OBDII code P279A in a 2018 Chevrolet Silverado?

The cost of repairs for this code can vary depending on the specific cause of the issue and the labor rates in your area. However, it is advisable to budget for potential costs related to parts replacement, diagnostic testing, and labor charges from a qualified mechanic or dealership.

7. Can a DIY enthusiast fix OBDII code P279A in a 2018 Chevrolet Silverado?

While some aspects of diagnosing and repairing this code may be possible for experienced DIY enthusiasts, it is recommended to seek professional help for complex issues related to the four-wheel drive system. Working with specialized tools and knowledge is crucial to ensure the problem is resolved correctly.

8. How long does it typically take to repair OBDII code P279A in a 2018 Chevrolet Silverado?

The duration of repairs for this code can vary based on the specific cause of the issue and the availability of parts. In general, it may take a few hours to a full day for a qualified mechanic to diagnose, repair, and test the four-wheel drive system to ensure it is functioning correctly.

9. Are there any recalls or technical service bulletins related to OBDII code P279A in a 2018 Chevrolet Silverado?

It is recommended to check with a Chevrolet dealership or visit the National Highway Traffic Safety Administration (NHTSA) website to see if there are any recalls or technical service bulletins related to this specific OBDII code in your vehicle model year.

10. How can I prevent OBDII code P279A from occurring in my 2018 Chevrolet Silverado in the future?

To prevent this code from occurring, it is essential to perform regular maintenance on the four-wheel drive system, such as checking and replacing transfer case fluid as recommended, addressing any warning lights or unusual symptoms promptly, and following the manufacturer's guidelines for driving in different modes to avoid strain on the system.