U0079 - Control Module Communication Bus "A" Off

Quick Answer

U0079 means: U0079 indicates a communication failure between control modules in your vehicle.

Fix: Check and replace faulty components Cost: $150 - $500 Time: 90-180 minutes

Can I drive with U0079? Immediate attention is recommended to avoid further electrical issues.

Common Questions

What does U0079 mean and how does it affect my car?

U0079 indicates a problem with communication between the vehicle's control modules. This can lead to issues like reduced engine performance, erratic behavior of safety features, and even complete vehicle shutdown. It's critical to address this issue promptly to avoid further complications.

What are the most common causes of U0079 and how much does it cost to fix?

Common causes of U0079 include damaged wiring, faulty control modules, and poor battery connections. Repair costs can vary significantly, ranging from $150 for wiring repairs to over $1,200 for control module replacements.

Can I drive my car with U0079 or should I stop immediately?

While you may be able to drive your vehicle with U0079, it is not advisable as it can lead to more severe problems. Ignoring this code can result in safety features failing, making your vehicle less safe to drive.

How can I diagnose U0079 myself using GeekOBD APP?

To diagnose U0079 with GeekOBD APP, start by running a full OBD2 scan to retrieve all stored codes. Check the freeze frame data for context on when the fault occurred, and look for patterns or other related codes that may indicate specific module issues.

What vehicles are most commonly affected by U0079?

U0079 is often reported in vehicles from manufacturers like Ford, Chevrolet, and Jeep, particularly in models from 2013 to 2018 that have advanced electronic systems.

How can I prevent U0079 from happening again?

To avoid future occurrences of U0079, regularly check and maintain your vehicle’s battery connections, inspect wiring for wear or corrosion, and keep software updated through regular dealer visits or service appointments.

What is U0079?

The diagnostic trouble code (DTC) U0079 indicates a communication issue within the Control Module Communication Bus A in a vehicle's network. This bus is crucial for the proper functioning of various modules, including engine control, transmission control, and ABS. When U0079 is triggered, it usually means that one or more control modules are unable to communicate with each other, which can lead to multiple system failures. This could manifest in various operational issues, like erratic engine performance, malfunctioning safety features, or even complete vehicle immobilization. Technically, this code is often related to wiring problems, faulty connectors, or even a malfunctioning control module itself. It is important for car owners to acknowledge that ignoring this code can lead to progressive electrical issues and potentially dangerous driving conditions. Commonly found in vehicles like the 2013-2018 Ford F-150 and 2014-2016 Chevrolet Silverado, U0079 could also appear in many other makes and models, particularly those with complex electronic systems. Proper diagnosis and timely repairs are crucial to maintaining vehicle functionality and safety.

System: U - Network (Communication, CAN Bus)

Symptoms

Common symptoms when U0079 is present:

  • The check engine light illuminates and stays on constantly, indicating an underlying issue that needs addressing.
  • Engine performance is erratic, with hesitations during acceleration or stalling while driving, making the vehicle difficult to control.
  • Fuel economy may decrease significantly, often by 10-15%, due to the engine running inefficiently as a result of communication errors.
  • Dashboard warning lights for various systems may light up, confusing the driver as to what the actual issue could be.
  • In some cases, safety features like ABS or traction control may become inoperative, leading to compromised vehicle safety.

Possible Causes

Most common causes of U0079 (ordered by frequency):

  1. The most common cause of U0079 is damaged or corroded wiring and connectors, which is likely to occur in 40% of cases. Regular inspections can help prevent this.
  2. Another frequent cause is a malfunctioning control module, which can account for about 30% of occurrences. If a module is not responding, it may need reprogramming or replacement.
  3. Poor battery connections or a weak battery can also trigger U0079, accounting for roughly 20% of cases. Ensuring a fully charged and well-connected battery can prevent this.
  4. Less commonly, software glitches or updates may lead to communication errors between modules, which can be resolved through a simple reflash of the software.
  5. In rare cases, physical damage to the control module due to impact or water ingress can cause U0079, although this is less than 5% of incidents.

U0079 Repair Costs

Cost Breakdown by Repair Type

Wiring Repair or Replacement

Repairing or replacing damaged wiring or connectors can restore communication in the bus system.

  • Total: $150 - $500
  • Success rate: 85%
Control Module Replacement

Replacing a faulty control module that has failed communication.

  • Total: $300 - $1,200
  • Success rate: 90%
Software Update

Reflashing or updating existing software to fix communication issues.

  • Total: $100 - $200
  • Success rate: 70%
Money-Saving Tips for U0079
  • Start with the most common and least expensive repairs first
  • Use GeekOBD APP to confirm diagnosis before replacing expensive parts
  • Consider preventive maintenance to avoid future occurrences
  • Compare prices for OEM vs aftermarket parts based on your needs
  • Address the issue promptly to prevent more expensive secondary damage

Diagnostic Steps

Professional U0079 Diagnosis Process

Follow these systematic steps to accurately diagnose U0079. Each step builds on the previous one to ensure accurate diagnosis.

Step 1: Step 1: Initial visual inspection - Check for obvious signs like damaged wiring, loose connections, or corrosion (5-10 minutes)

Step 1: Initial visual inspection - Check for obvious signs like damaged wiring, loose connections, or corrosion (5-10 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 2: Step 2: OBD2 scan with GeekOBD APP - Retrieve all codes and freeze frame data to understand the fault context (10-15 minutes)

Step 2: OBD2 scan with GeekOBD APP - Retrieve all codes and freeze frame data to understand the fault context (10-15 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 3: Step 3: Component testing - Use a multimeter or specific diagnostic tools to test suspected components (20-30 minutes)

Step 3: Component testing - Use a multimeter or specific diagnostic tools to test suspected components (20-30 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 4: Step 4: System function test - Verify proper operation after repairs and clear codes (10-15 minutes)

Step 4: System function test - Verify proper operation after repairs and clear codes (10-15 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 5: Step 5: Road test verification - Drive vehicle under various conditions to confirm repair success (15-20 minutes)

Step 5: Road test verification - Drive vehicle under various conditions to confirm repair success (15-20 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.

Important Notes

  • Always verify the repair with GeekOBD APP after completing diagnostic steps
  • Clear codes and test drive to ensure the problem is resolved
  • Address underlying causes to prevent code recurrence

Real Repair Case Studies

Case Study 1: 2015 Ford F-150 Communication Failure

Vehicle: 2015 Ford F-150, 75,000 miles

Problem: Customer reported intermittent check engine light and engine stalling.

Diagnosis: After running the GeekOBD APP scan, U0079 was found. Visual inspection revealed corroded wiring in the harness.

Solution: Replaced the damaged wiring harness and ensured proper connections.

Cost: $250 for parts and labor

Result: The vehicle's performance improved, and the check engine light remained off after multiple tests.

Case Study 2: 2016 Chevrolet Silverado Module Replacement

Vehicle: 2016 Chevrolet Silverado, 50,000 miles

Problem: Customer experienced engine performance issues and multiple warning lights.

Diagnosis: Diagnostic scan confirmed U0079 alongside other codes. Testing indicated a faulty engine control module.

Solution: Replaced the control module and reprogrammed it to match vehicle specifications.

Cost: $800 for parts and labor

Result: Post-repair, the vehicle operated smoothly with no warning lights.

Diagnose U0079

Use GeekOBD APP for professional diagnosis!

  • Real-time data monitoring
  • Advanced diagnostic features
  • Step-by-step repair guidance
  • Professional-grade analysis
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Code Information

Code: U0079
System: Network (Communication, CAN Bus)
Severity: HIGH
Category: Network Codes