Quick Answer
U0879 means: U0879 indicates a lost communication link between vehicle control modules.
Can I drive with U0879? Immediate attention is recommended to avoid further issues.
Common Questions
What does U0879 mean and how does it affect my car?
U0879 signifies a communication failure between control modules in your vehicle. This can lead to various malfunctions, including erratic transmission behavior and decreased fuel efficiency. Ignoring this code can lead to more severe problems and safety risks.
What are the most common causes of U0879 and how much does it cost to fix?
Common causes include faulty wiring (40% likelihood), defective control modules (30%), and software issues. Repair costs can range from $150 for wiring repairs to $1200 for module replacements based on the severity of the issue.
Can I drive my car with U0879 or should I stop immediately?
It is advisable to stop driving your vehicle if you see the U0879 code. Continuing to drive can exacerbate the issue, potentially leading to severe performance problems or safety hazards.
How can I diagnose U0879 myself using GeekOBD APP?
To diagnose U0879 with the GeekOBD APP, connect the device to your vehicle's OBD2 port, scan for codes, and review freeze frame data to identify when the issue occurs. This will help you understand the context and potential causes.
What vehicles are most commonly affected by U0879?
U0879 is frequently seen in 2015-2018 Chevrolet Silverado and GMC Sierra models, as well as some Cadillac and Buick vehicles from the same production years.
How can I prevent U0879 from happening again?
Regularly inspect wiring and connectors during maintenance, keep your vehicle's software updated, and address any electrical issues promptly to prevent future occurrences of U0879.
What is U0879?
The diagnostic trouble code U0879 indicates a communication issue between the vehicle’s control modules. Specifically, this code means that one control module cannot communicate with another module, leading to potential performance issues. In modern vehicles, different systems such as the engine control module (ECM), transmission control module (TCM), and various body control modules rely on a network to share crucial information. When one module fails to transmit data, it can create a ripple effect, affecting vehicle performance, fuel efficiency, and safety features. For instance, if the TCM is unable to communicate with the ECM, you might experience transmission shifting issues. This code is particularly common in vehicles like the Chevrolet Silverado from 2015 to 2018, which have a complex network of modules. Ignoring this code can lead to more severe issues, such as stalling or failure of critical components, making it essential to address it promptly. Understanding the underlying reasons for this communication failure can save car owners from costly repairs and frustrating breakdowns, ensuring a safer driving experience.
System: U - Network (Communication, CAN Bus)
Symptoms
Common symptoms when U0879 is present:
- Check engine light illuminated, often remaining on until the issue is resolved.
- Erratic transmission behavior, such as harsh shifting or slipping, which can be alarming during driving.
- Decreased fuel economy, with reports of a 10-15% drop due to inefficient communication between modules.
- Inconsistent performance of safety features, such as ABS or traction control, making the vehicle less safe.
- Failure to start, as the vehicle may not be able to communicate necessary start-up parameters.
Possible Causes
Most common causes of U0879 (ordered by frequency):
- Faulty wiring or connectors, estimated at 40% likelihood, which can lead to intermittent communication failures.
- Defective control module, with around 30% likelihood; replacing a malfunctioning module is often necessary.
- Software issues or outdated firmware causing communication errors, which can be resolved with a simple update.
- Less common but serious cause: water intrusion in connectors, which can lead to severe electrical issues.
- Rare cause: manufacturing defects in the control modules, potentially covered under warranty in some cases.
U0879 Repair Costs
Cost Breakdown by Repair Type
Wiring Repair
Repair or replacement of damaged wiring or connectors to restore communication.
- Total: $150 - $300
- Success rate: 85%
Control Module Replacement
Replacing a faulty control module with a new or refurbished unit.
- Total: $500 - $1200
- Success rate: 90%
Software Update
Performing a software update to rectify communication errors.
- Total: $100 - $200
- Success rate: 70%
Money-Saving Tips for U0879
- 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 U0879 Diagnosis Process
Follow these systematic steps to accurately diagnose U0879. 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).
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).
Step 3: Step 3: Component testing - Use a multimeter or specific diagnostic tools to test suspected components, focusing on communication lines (20-30 minutes)
Step 3: Component testing - Use a multimeter or specific diagnostic tools to test suspected components, focusing on communication lines (20-30 minutes).
Step 4: Step 4: System function test - Verify proper operation after repairs and clear codes to check if the issue persists (10-15 minutes)
Step 4: System function test - Verify proper operation after repairs and clear codes to check if the issue persists (10-15 minutes).
Step 5: Step 5: Road test verification - Drive the vehicle under various conditions to confirm repair success and monitor module functionality (15-20 minutes)
Step 5: Road test verification - Drive the vehicle under various conditions to confirm repair success and monitor module functionality (15-20 minutes).
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: Chevrolet Silverado 2017 - Communication Error Resolved
Vehicle: 2017 Chevrolet Silverado 1500, 65,000 miles
Problem: Customer reported intermittent check engine light and poor transmission performance.
Diagnosis: After scanning with GeekOBD APP, U0879 was confirmed. A visual inspection revealed damaged wiring under the dashboard.
Solution: Repaired the damaged wiring and cleared the codes. Conducted a road test, confirming normal function.
Cost: $250 (wiring repair and labor)
Result: Customer reported improved transmission performance and no further check engine light.
Case Study 2: GMC Sierra 2016 - Module Replacement
Vehicle: 2016 GMC Sierra 2500 HD, 80,000 miles
Problem: Vehicle would not start, accompanied by U0879 code.
Diagnosis: OBD2 scan indicated U0879, requiring further inspection of the control modules.
Solution: Replaced the faulty ECM and updated the software. Conducted a full system check.
Cost: $950 (including module and software update)
Result: Vehicle started immediately post-repair and operated normally.