Quick Answer
U0771 means: U0771 indicates a communication error between vehicle control modules.
Can I drive with U0771? Immediate attention is recommended to prevent further issues.
Common Questions
What does U0771 mean and how does it affect my car?
U0771 indicates a communication error between your vehicle's control modules. This can lead to various performance issues, including erratic engine behavior, dashboard alerts, and reduced functionality of electronic features. If left unresolved, it can escalate into more significant mechanical problems.
What are the most common causes of U0771 and how much does it cost to fix?
Common causes of U0771 include faulty wiring (40% likelihood), defective control modules (30%), and necessary software updates (15%). Repair costs can range from $150 for wiring repairs to $1200 for control module replacements, depending on the issue.
Can I drive my car with U0771 or should I stop immediately?
It is recommended to stop driving your vehicle if you see the U0771 code. Continuing to drive could exacerbate the issue and lead to more severe damage or safety hazards.
How can I diagnose U0771 myself using GeekOBD APP?
Using the GeekOBD APP, you can perform a diagnostic scan to retrieve the U0771 code and any related codes. Make sure to check the freeze frame data for additional context on when the error occurred, and inspect the wiring and connectors based on the findings.
What vehicles are most commonly affected by U0771?
U0771 is frequently seen in 2015-2019 Ford vehicles, including the Ford F-150 and Ford Explorer. These models are known to have issues with communication lines due to electrical system design.
How can I prevent U0771 from happening again?
To avoid U0771 in the future, regularly inspect the vehicle's wiring and connectors for damage, keep software up to date, and avoid installing aftermarket accessories that could interfere with the electrical system.
What is U0771?
Diagnostic Trouble Code (DTC) U0771 indicates that there is a communication issue between the vehicle's control modules, specifically related to a miscommunication in the data bus line. This code often appears when the vehicle's Engine Control Module (ECM) or Transmission Control Module (TCM) is unable to communicate with other modules, such as the Body Control Module (BCM) or the Anti-lock Braking System (ABS). In practical terms, when U0771 is triggered, it can lead to a variety of performance issues. Drivers may notice unusual behaviors such as erratic shifting, dashboard warnings, or even the engine stalling. The most common scenario is that the check engine light illuminates, prompting the need for a diagnostic scan. This code can also lead to reduced vehicle functionality, such as the inability to use certain electronic features like the power windows or radio. The implications of ignoring this code can escalate, potentially leading to further electrical issues or even a complete failure of the vehicle's electronic systems. It’s crucial to address U0771 promptly to avoid more severe damage and ensure the vehicle operates smoothly and safely.
System: U - Network (Communication, CAN Bus)
Symptoms
Common symptoms when U0771 is present:
- Check engine light stays on constantly, indicating an issue that requires immediate diagnostics.
- Engine hesitates during acceleration, which can lead to unsafe driving conditions.
- Fuel economy decreased by 10-15%, resulting in more frequent trips to the gas station.
- Dashboard warning lights may illuminate, including ABS or traction control alerts.
- Certain electronic features, such as power windows or the radio, may become non-functional.
Possible Causes
Most common causes of U0771 (ordered by frequency):
- Faulty wiring or connectors in the communication line (estimated 40% likelihood). Damaged or corroded wiring can disrupt signals.
- Defective control module (estimated 30% likelihood). If a specific module fails, it can prevent communication with others.
- Software glitches or updates needed for the modules (estimated 15% likelihood). Keeping software up to date can prevent this.
- Less common cause includes electrical interference from aftermarket accessories, which can disrupt communication.
- Rare but possible cause is a complete electrical system failure due to a failing battery or alternator.
U0771 Repair Costs
Cost Breakdown by Repair Type
Wiring Repair or Replacement
Repairing or replacing damaged wiring and connectors in the communication line.
- Total: $150 - $500
- Success rate: 85%
Control Module Replacement
Replacing a faulty control module that is causing communication errors.
- Total: $300 - $1200
- Success rate: 90%
Software Update
Performing a software update on modules to correct communication issues.
- Total: $50 - $200
- Success rate: 70%
Money-Saving Tips for U0771
- 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 U0771 Diagnosis Process
Follow these systematic steps to accurately diagnose U0771. 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 multimeter or specific diagnostic tools to test suspected components (20-30 minutes)
Step 3: Component testing - Use multimeter or specific diagnostic tools to test suspected components (20-30 minutes).
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).
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).
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: Wiring Repair on a 2016 Ford F-150
Vehicle: 2016 Ford F-150, 45,000 miles
Problem: Customer reported check engine light and intermittent power window issues.
Diagnosis: Performed an OBD2 scan and retrieved U0771. Inspected wiring and found frayed wires in the communication line.
Solution: Repaired the damaged wiring and cleared the code. Conducted a road test to ensure functionality.
Cost: $200 (including labor and parts)
Result: Customer reported full functionality restored and no further issues.
Case Study 2: Control Module Replacement on a 2018 Ford Explorer
Vehicle: 2018 Ford Explorer, 30,000 miles
Problem: Vehicle would not shift properly and had multiple dashboard alerts.
Diagnosis: OBD2 scan revealed U0771 along with other related codes. Module testing indicated a faulty TCM.
Solution: Replaced the Transmission Control Module and updated software.
Cost: $950 (including parts and labor)
Result: Vehicle performance returned to normal, with no further errors reported.