AutoCodes – GMC – B0408 2016 GMC Sierra

B0408 2016 GMC Sierra Code - Main Temperature Control Circuit

Quick Answer

Stepper motors are used for temperature regulation, air distribution control and recirculation door control. Common causes include Faulty Air Temperature Actuator, Air Temperature Actuator harness is open or shorted, Air Temperature Actuator circuit poor electrical connection. Severity is Low - monitor the vehicle and repair when practical. The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

What it means: B0408 2016 GMC Sierra indicates Main Temperature Control Circuit.
Common causes: Common causes include Faulty Air Temperature Actuator, Air Temperature Actuator harness is open or shorted, Air Temperature Actuator circuit poor electrical connection.
Severity: Low - monitor the vehicle and repair when practical.
Can I drive?: The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

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Code Popularity 250

How popular is this code, among other codes? Low

Repair Importance Level

Low (Monitor) (1 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 29, 2024

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code B0408 2016 GMC Sierra Description

Stepper motors are used for temperature regulation, air distribution control and recirculation door control. With the switches and dials on the HVAC controls, air temperature door position, mode door position and recirculation door position can be selected. The selected values are passed to the Heating, Ventilation, and Air Conditioning (HVAC) Control Module via serial data. The HVAC control module supplies a 12 V reference voltage to the stepper motors and energizes the 4 stepper motor coils with a pulsed ground signal. The stepper motors move the appropriate doors into the calculated positions, in order to reach the desired positions.

OBDII Code B0408 2016 GMC Sierra - Main Temperature Control Circuit - AutoCodes.com — B0408 2016 GMC Sierra Code - Main Temperature Control Circuit

What does this mean?

What are the Possible Causes of the DTC B0408 2016 GMC Sierra?

Faulty Air Temperature Actuator
Air Temperature Actuator harness is open or shorted
Air Temperature Actuator circuit poor electrical connection
Faulty Heating, Ventilation, and Air Conditioning (HVAC) Control Module

How to Fix the DTC B0408 2016 GMC Sierra?

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 does this mean?

Code Tech Notes

B0413:02 Main Temperature Control Circuit Short to Ground
B0413:05 Main Temperature Control Circuit Short to Battery or Open
B0413:61 Main Temperature Control Circuit Actuator Stuck Open

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B0408 2016 GMC Sierra 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 B0408 2016 GMC Sierra code?

Need more information on how to fix the B0408 2016 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the 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 B0408 2016 GMC Sierra Code

1. What does OBDII code B0408 on a 2016 GMC Sierra indicate?

Code B0408 refers to a fault in the Main Temperature Control Circuit of the HVAC system in the vehicle.

2. What are the common symptoms of OBDII code B0408 in a 2016 GMC Sierra?

Common symptoms include inconsistent temperature control from the HVAC system, the inability to adjust the temperature, or the system blowing only hot or cold air.

3. What are the possible causes of OBDII code B0408 in a 2016 GMC Sierra?

Possible causes include a malfunctioning blend door actuator, a faulty HVAC control module, wiring issues, or a failed temperature sensor.

4. How can I diagnose the Main Temperature Control Circuit issue causing OBDII code B0408 on my 2016 GMC Sierra?

Diagnosis typically involves checking the blend door actuator for proper operation, inspecting the wiring and connectors for any damage, and testing the HVAC control module and temperature sensor.

5. Can I continue driving my 2016 GMC Sierra with OBDII code B0408 present?

While the vehicle may still be operable with this code, it is recommended to address the issue promptly to avoid potential discomfort from the HVAC system malfunctioning.

6. How can I repair OBDII code B0408 on my 2016 GMC Sierra?

Repair options may include replacing the blend door actuator, repairing or replacing damaged wiring, resetting the HVAC control module, or replacing the temperature sensor.

7. Is it possible to reset OBDII code B0408 in a 2016 GMC Sierra without fixing the underlying issue?

While clearing the code may temporarily turn off the check engine light, the underlying problem causing the code will persist and likely trigger the code again in the future.

8. Are there any DIY tips for addressing OBDII code B0408 in a 2016 GMC Sierra?

DIY tips may include checking and securing any loose or damaged wiring, ensuring proper connection of components, and following the vehicle's service manual for specific troubleshooting steps.

9. How much should I expect to pay for professional repairs related to OBDII code B0408 on a 2016 GMC Sierra?

Costs can vary depending on the exact cause of the issue, but expect to pay for parts and labor, with total repair costs potentially ranging from a hundred to several hundred dollars.

10. Can OBDII code B0408 on a 2016 GMC Sierra cause any other problems if left unresolved?

Leaving this code unresolved may lead to continued HVAC system issues, potential discomfort while driving, and could affect the overall climate control functionality of the vehicle.