U039B - Communication Error with Battery Energy Control Module (BECM) in Ford and Honda Vehicles

Quick Answer

U039B means: U039B indicates a communication failure between the ECU and the Battery Energy Control Module.

Fix: Check and replace faulty components Cost: $100 - $300 Time: 90-180 minutes

Can I drive with U039B? Immediate attention is recommended to prevent performance degradation.

Common Questions

What does U039B mean and how does it affect my car?

U039B indicates a communication failure between your engine control unit and the Battery Energy Control Module. This can lead to reduced performance, lower fuel efficiency, and potential safety concerns, particularly in hybrid vehicles.

What are the most common causes of U039B and how much does it cost to fix?

Common causes include faulty wiring (60% likelihood), software glitches (20%), and failed BECM (10%). Repair costs can range from $100 for wiring repairs to $800 for a BECM replacement.

Can I drive my car with U039B or should I stop immediately?

While you may be able to drive short distances, it's advisable to stop and address the issue sooner rather than later to prevent further damage or safety risks.

How can I diagnose U039B myself using GeekOBD APP?

You can use the GeekOBD APP to scan for DTCs, view freeze frame data, and monitor real-time vehicle parameters. Look for any communication errors related to BECM.

What vehicles are most commonly affected by U039B?

Commonly affected vehicles include the 2011-2015 Ford Fusion Hybrid and the 2013-2016 Honda Accord Hybrid. Always check for recalls or Technical Service Bulletins (TSBs) related to your specific model.

How can I prevent U039B from happening again?

Regular vehicle maintenance, ensuring all electrical connections are secure, and avoiding aftermarket electrical modifications can help prevent future occurrences of U039B.

What is U039B?

The diagnostic trouble code (DTC) U039B signifies a communication error between the engine control unit (ECU) and the Battery Energy Control Module (BECM). This code is particularly common in certain models from Ford and Honda, especially those equipped with hybrid systems. When a U039B code is triggered, it typically means that the ECU is unable to receive or send data to the BECM, which can impact the vehicle’s performance and efficiency. In hybrid vehicles, the BECM plays a crucial role in managing the battery's energy distribution, so any disruption in communication can lead to performance issues, reduced fuel efficiency, and potential safety concerns. Real-world implications of a U039B code include the vehicle entering a low-power mode or 'limp' mode to prevent further issues. In some cases, drivers may notice the check engine light illuminated, and the vehicle may exhibit symptoms such as decreased acceleration or engine stalling. It's important to address this issue promptly to avoid further damage or costly repairs down the line.

System: U - Network (Communication, CAN Bus)

Symptoms

Common symptoms when U039B is present:

  • Check engine light stays on constantly, indicating a persistent issue requiring diagnosis.
  • Engine hesitates during acceleration, leading to a noticeable lag that can be frustrating for drivers.
  • Fuel economy decreased by 10-15%, which can significantly impact your budget over time.
  • Battery warning light activates, suggesting potential issues with the hybrid system.
  • Unresponsive dashboard indicators, affecting the driver's ability to monitor vehicle systems.

Possible Causes

Most common causes of U039B (ordered by frequency):

  1. Faulty wiring or connectors (60% likelihood) - Corroded or damaged connections can interrupt communication between the ECU and BECM.
  2. Software glitches (20% likelihood) - Outdated or corrupt software can cause communication errors.
  3. Failed BECM (10% likelihood) - A malfunctioning Battery Energy Control Module may need replacement.
  4. Interference from aftermarket modifications (5% likelihood) - Non-OEM parts can disrupt system communication.
  5. Rare but possible: ECU failure (5% likelihood) - In some cases, the engine control unit itself may be faulty.

U039B Repair Costs

Cost Breakdown by Repair Type

Wiring and Connector Repair

Repairing or replacing corroded wiring and connectors to restore communication.

  • Total: $100 - $300
  • Success rate: 85%
BECM Replacement

Replacing the Battery Energy Control Module if it's determined to be faulty.

  • Total: $400 - $800
  • Success rate: 90%
Software Update

Updating the vehicle’s software to rectify glitches causing communication errors.

  • Total: $50 - $150
  • Success rate: 75%
Money-Saving Tips for U039B
  • 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 U039B Diagnosis Process

Follow these systematic steps to accurately diagnose U039B. 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 multimeter or specific diagnostic tools to test suspected components, focusing on wiring and connectors (20-30 minutes)

Step 3: Component testing - Use multimeter or specific diagnostic tools to test suspected components, focusing on wiring and connectors (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, ensuring the issue does not reoccur (15-20 minutes)

Step 5: Road test verification - Drive vehicle under various conditions to confirm repair success, ensuring the issue does not reoccur (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: Repair Case Study: 2013 Ford Fusion Hybrid

Vehicle: 2013 Ford Fusion Hybrid, 85,000 miles

Problem: Customer reported a persistent check engine light and reduced performance.

Diagnosis: Diagnostic scan revealed U039B. Inspection found corroded wiring leading to the BECM.

Solution: Replaced damaged wiring and connectors; cleared codes and performed a system function test.

Cost: $250 (including parts and labor)

Result: Customer reported improved performance and fuel efficiency post-repair.

Case Study 2: Repair Case Study: 2016 Honda Accord Hybrid

Vehicle: 2016 Honda Accord Hybrid, 60,000 miles

Problem: Customer experienced engine hesitation and battery warning light activation.

Diagnosis: Found U039B through OBD2 scan; determined BECM needed replacement.

Solution: Replaced the BECM and updated the vehicle software to ensure proper function.

Cost: $750 (including parts and labor)

Result: Vehicle performance returned to normal, with no further issues reported.

Diagnose U039B

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: U039B
System: Network (Communication, CAN Bus)
Severity: HIGH
Category: Network Codes