Quick Answer
U0859 means: U0859 signifies a communication breakdown between vehicle control modules.
Can I drive with U0859? Immediate attention is recommended to prevent further issues.
Common Questions
What does U0859 mean and how does it affect my car?
The U0859 code indicates that there's a communication failure between control modules in your vehicle, which can lead to erratic behaviors in systems like ABS or engine management. If not addressed, this could escalate into more serious safety issues.
What are the most common causes of U0859 and how much does it cost to fix?
Common causes include wiring issues, faulty modules, and grounding problems. Repair costs can range from $150 for wiring repairs to $800 for module replacements, depending on the specific issue.
Can I drive my car with U0859 or should I stop immediately?
While you may be able to drive your vehicle with the U0859 code, it's advisable to seek immediate attention. Continued driving could worsen the problem and potentially compromise safety features.
How can I diagnose U0859 myself using GeekOBD APP?
Using GeekOBD APP, you can connect to your vehicle's OBD2 port to retrieve diagnostic codes and freeze frame data, helping you pinpoint the exact issue causing the U0859 code.
What vehicles are most commonly affected by U0859?
Vehicles like the 2015-2020 Chevrolet Silverado, GMC Sierra, and Cadillac Escalade are frequently affected by the U0859 code due to their complex communication networks.
How can I prevent U0859 from happening again?
Regular vehicle maintenance, including checking wiring and connectors, can help prevent U0859. Additionally, ensure software updates are performed on your vehicle’s modules to keep them functioning optimally.
What is U0859?
The diagnostic trouble code (DTC) U0859 indicates a communication issue within the vehicle's communication network, specifically that the control module is unable to communicate with another module. This is often linked to issues within the CAN (Controller Area Network) bus, which is responsible for allowing different modules in your vehicle to communicate. Commonly affected vehicles include the 2015-2020 Chevrolet Silverado, GMC Sierra, and Cadillac Escalade. If you see this code, it typically means there is a problem with the wiring, connectors, or possibly a malfunctioning module. In practical terms, this can lead to various issues, including malfunctions in crucial systems like the ABS, traction control, or even the engine management system. Ignoring the U0859 code could lead to further complications and even affect the vehicle's safety features. Therefore, it’s essential to address this code promptly to ensure that all modules are functioning correctly and to avoid more extensive and costly repairs down the line.
System: U - Network (Communication, CAN Bus)
Symptoms
Common symptoms when U0859 is present:
- Check engine light remains illuminated, indicating a fault detected by the vehicle's computer systems.
- Increased difficulty in controlling vehicle systems, such as erratic behavior in power steering or ABS activation.
- Loss of functionality in various electrical systems, like power windows or infotainment systems, which may stop working intermittently.
- Dashboard warning lights appearing randomly, which can confuse the driver about the vehicle's actual condition.
- Sudden drops in fuel economy or performance issues, especially noticeable during acceleration or uphill driving.
Possible Causes
Most common causes of U0859 (ordered by frequency):
- Wiring issues between the modules (60% likelihood) - Corroded, damaged, or loose connections can disrupt communication.
- Faulty control module (25% likelihood) - A malfunctioning module may fail to send or receive data correctly.
- Grounding problems (10% likelihood) - Poor grounding can lead to erratic electrical behavior and communication failures.
- Intermittent faults due to environmental factors (3% likelihood) - Temperature extremes or moisture can temporarily affect module communication.
- Rarely, software glitches (2% likelihood) - Outdated or corrupted software in the module can lead to communication errors.
U0859 Repair Costs
Cost Breakdown by Repair Type
Wiring Repair
Repairing or replacing damaged wiring or connectors in the communication network.
- Total: $150 - $400
- Success rate: 80%
Control Module Replacement
Replacing a faulty control module that is not communicating properly.
- Total: $300 - $800
- Success rate: 95%
Grounding Repair
Fixing grounding issues that may lead to communication errors.
- Total: $100 - $250
- Success rate: 70%
Money-Saving Tips for U0859
- 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 U0859 Diagnosis Process
Follow these systematic steps to accurately diagnose U0859. Each step builds on the previous one to ensure accurate diagnosis.
Step 1: Step 1: Initial visual inspection - Look for damaged wiring, loose connectors, or signs of corrosion, which can take about 5-10 minutes
Step 1: Initial visual inspection - Look for damaged wiring, loose connectors, or signs of corrosion, which can take about 5-10 minutes.
Step 2: Step 2: OBD2 scan with GeekOBD APP - Use the app to identify all codes and review freeze frame data for context, taking approximately 10-15 minutes
Step 2: OBD2 scan with GeekOBD APP - Use the app to identify all codes and review freeze frame data for context, taking approximately 10-15 minutes.
Step 3: Step 3: Component testing - Employ a multimeter or specific diagnostic tools to check the functionality of suspected components, which could take 20-30 minutes
Step 3: Component testing - Employ a multimeter or specific diagnostic tools to check the functionality of suspected components, which could take 20-30 minutes.
Step 4: Step 4: System function test - After any repairs, verify that all systems are operational and clear codes using GeekOBD APP, requiring about 10-15 minutes
Step 4: System function test - After any repairs, verify that all systems are operational and clear codes using GeekOBD APP, requiring about 10-15 minutes.
Step 5: Step 5: Road test verification - Drive the vehicle under various conditions to confirm that the issue has been resolved, which can last 15-20 minutes
Step 5: Road test verification - Drive the vehicle under various conditions to confirm that the issue has been resolved, which can last 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: Communication Issue Fixed in 2016 Chevrolet Silverado
Vehicle: 2016 Chevrolet Silverado, 75,000 miles
Problem: Customer reported check engine light and intermittent ABS activation.
Diagnosis: Diagnostics revealed a U0859 code. Visual inspection showed corroded wiring under the dashboard.
Solution: Replaced damaged wiring and secured loose connectors.
Cost: $200 (including labor and parts)
Result: Check engine light cleared and ABS function restored.
Case Study 2: Control Module Replacement in 2018 GMC Sierra
Vehicle: 2018 GMC Sierra, 50,000 miles
Problem: Customer experienced loss of power steering and dashboard warning lights.
Diagnosis: U0859 code indicated communication issues; further testing isolated the problem to a faulty control module.
Solution: Replaced the power steering control module with OEM part.
Cost: $600 (including parts and labor)
Result: Vehicle performance restored and all systems functioning normally.