AutoCodes – GMC – B0239 GMC

B0239 GMC Code - Air Flow Control 1 Circuit Performance

Quick Answer

The Heating, Ventilation, and Air Conditioning (HVAC) Control Module controls the HVAC actuators to regulate the airflow and temperature through the HVAC system. Common causes include Faulty Defrost Actuator, Defrost Actuator harness is open or shorted, Defrost 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: B0239 GMC indicates Air Flow Control 1 Circuit Performance.
Common causes: Common causes include Faulty Defrost Actuator, Defrost Actuator harness is open or shorted, Defrost 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 675

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 10, 2021

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B0239 GMC Description

The Heating, Ventilation, and Air Conditioning (HVAC) Control Module controls the HVAC actuators to regulate the airflow and temperature through the HVAC system. The actuators are 2 wire, bi-directional electric motors that share the same common control circuit. When the operator adjusts the actuators, the control module can only operate one actuator at a time due to the shared common control circuit. The control circuits use either a 0 or 12-volt value to co-ordinate the actuator movement. The HVAC control module reverses the polarity of the control circuits to move the actuator in the opposite direction.
The HVAC control module determines the door position by counting motor pulses on one of the control circuits. The HVAC control module converts the pulses to counts with a range of 0-255 counts.
When a calibration or recalibration procedure is performed, the HVAC control module calculates the door travel range. The HVAC control module compares the total number of pulses to calibrated limits. If the total pulse count is less than or equal to the maximum calibrated limited and more that or equal to the minimum calibrated limit, then the calibration is considered successful.

OBDII Code B0239 GMC - Air Flow Control 1 Circuit Performance - AutoCodes.com — B0239 GMC Code - Air Flow Control 1 Circuit Performance

What does this mean?

What are the Possible Causes of the DTC B0239 GMC?

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

How to Fix the DTC B0239 GMC?

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 B0239 GMC 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 B0239 GMC code?

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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 B0239 GMC Code

1. What are the common symptoms of OBDII code B0239 GMC (Air Flow Control 1 Circuit Performance)?

- Common symptoms include rough idling, decreased fuel efficiency, engine stalling, and a noticeable decrease in engine performance.

2. What are some possible causes of OBDII code B0239 GMC?

- Possible causes include a faulty air flow control actuator, wiring issues, a vacuum leak in the intake system, or a problem with the intake manifold.

3. How can I diagnose the issue related to OBDII code B0239 GMC?

- To diagnose the issue, you can use a scan tool to check for the specific code, visually inspect the air flow control components, and perform a thorough inspection of the intake system for any leaks.

4. Can I still drive my vehicle with OBDII code B0239 GMC active?

- It is not recommended to drive your vehicle with this code active, as it can lead to further damage and potentially unsafe driving conditions.

5. How can I repair OBDII code B0239 GMC?

- The repair process for this code typically involves replacing the faulty air flow control actuator, repairing any damaged wiring, fixing vacuum leaks, or addressing issues with the intake manifold.

6. Will resetting the OBDII code B0239 GMC make it go away permanently?

- Resetting the code may temporarily clear the warning light, but if the underlying issue is not addressed, the code is likely to reappear once the vehicle is driven again.

7. Is it possible to prevent OBDII code B0239 GMC from occurring in the future?

- Performing regular maintenance on your vehicle, such as cleaning or replacing air filters, checking for vacuum leaks, and inspecting wiring connections, can help prevent this code from occurring.

8. Can a DIY enthusiast fix OBDII code B0239 GMC at home?

- Depending on your level of expertise and access to tools, some DIY enthusiasts may be able to address this code at home. However, more complex issues may require professional assistance.

9. How long does it typically take to repair OBDII code B0239 GMC?

- The repair time can vary depending on the specific cause of the code and the availability of replacement parts. In general, it may take a few hours to a full day to complete the repair.

10. What is the cost of repairing OBDII code B0239 GMC?

- The cost of repair can vary greatly depending on the specific cause of the code, the labor rates in your area, and the cost of replacement parts. It is recommended to obtain quotes from different mechanics or shops for an accurate estimate.