Quick Answer
B1391 means: B1391 indicates a malfunction in the body control module.
Can I drive with B1391? Immediate attention is recommended to prevent further electrical issues.
Common Questions
What does B1391 mean and how does it affect my car?
B1391 indicates a malfunction in your vehicle's body control module, which controls various electronic features. If this module fails, you may experience issues with lights, locks, and windows. Immediate diagnosis and repair are essential to avoid further complications.
What are the most common causes of B1391 and how much does it cost to fix?
The most frequent cause of B1391 is a faulty body control module, with replacement costs ranging from $300 to $800. Damaged wiring can also cause this code, with repair costs around $100 to $300. Regular maintenance can help prevent these issues.
Can I drive my car with B1391 or should I stop immediately?
While you may be able to drive, it’s not advisable as electrical failures can worsen, affecting safety features. It’s best to have the vehicle inspected as soon as possible to prevent larger issues.
How can I diagnose B1391 myself using GeekOBD APP?
To diagnose B1391, connect the GeekOBD APP to your vehicle's OBD2 port. Retrieve the trouble codes and check the freeze frame data for any abnormalities, which will help you understand the context of the fault.
What vehicles are most commonly affected by B1391?
B1391 is frequently seen in vehicles like the 2015-2018 Honda Accord and the 2016-2019 Toyota Camry. Always check for any recalls or technical service bulletins related to the BCM for your specific model.
How can I prevent B1391 from happening again?
To prevent B1391, ensure regular inspections of the electrical system, keep connections clean and dry, and address any signs of corrosion or wear as part of routine maintenance.
What is B1391?
The diagnostic trouble code B1391 indicates a malfunction in the body control module (BCM) of your vehicle, particularly common in models from Honda and Toyota, such as the 2015-2018 Honda Accord and the 2016-2019 Toyota Camry. The BCM is a crucial component responsible for managing various electronic functions in your vehicle, including lighting, power windows, and security systems. When the BCM fails or detects an abnormality, it triggers the B1391 code. This can lead to a range of issues including malfunctioning lights, non-responsive power accessories, or even problems with the vehicle's security system. Understanding this code is essential for diagnosing electrical issues effectively. If left unresolved, it could result in further electrical malfunctions or even leave your vehicle inoperable, making it critical to address promptly. Many drivers might notice symptoms like the dashboard warning lights illuminating, or functionality issues with windows or locks. Regular diagnostics can help catch these issues before they escalate, ensuring your vehicle runs smoothly and safely.
System: B - Body (Airbags, Lighting, Security, Climate Control)
Symptoms
Common symptoms when B1391 is present:
- Check engine light illuminates and remains on, indicating a significant fault in the vehicle's electrical system.
- Power windows may stop functioning intermittently, causing frustration and inconvenience for the driver.
- Security system may not engage properly, leading to concerns about vehicle theft or unauthorized access.
- Interior and exterior lights may flicker or fail, affecting visibility and safety.
- The vehicle may exhibit erratic behavior with other electronic components, such as door locks or dashboard displays.
Possible Causes
Most common causes of B1391 (ordered by frequency):
- Faulty body control module is the most common cause, occurring in about 70% of cases due to wear or electrical issues.
- Damaged wiring or poor connections can lead to communication errors, which account for roughly 20% of B1391 codes.
- Moisture intrusion in the BCM can cause corrosion and short circuits, potentially preventable with regular inspections.
- Less common causes include software glitches in the BCM, which may require a software update from a dealership.
- Rarely, external electrical interference or malfunctioning sensors can trigger this code, although this is not often seen.
B1391 Repair Costs
Cost Breakdown by Repair Type
BCM Replacement
Replacing the faulty body control module with a new or refurbished unit.
- Total: $300 - $800
- Success rate: 85%
Wiring Repair
Fixing damaged wiring or connections that are causing the BCM to malfunction.
- Total: $100 - $300
- Success rate: 75%
Money-Saving Tips for B1391
- 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 B1391 Diagnosis Process
Follow these systematic steps to accurately diagnose B1391. Each step builds on the previous one to ensure accurate diagnosis.
Step 1: Start with an initial visual inspection of the BCM and related wiring for any signs of damage or corrosion (5-10 minutes)
Step 2: Use an OBD2 scanner, such as the GeekOBD APP, to retrieve all trouble codes and freeze frame data, providing context for the B1391 code (10-15 minutes)
Step 3: Perform component testing using a multimeter to verify the functionality of the BCM and its connections (20-30 minutes)
Step 4: Conduct a system function test to ensure all related electrical functions operate correctly after repairs (10-15 minutes)
Step 5: Finally, perform a road test to confirm repair success under various driving conditions (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: BCM Replacement for a 2017 Honda Accord
Vehicle: 2017 Honda Accord, 65,000 miles
Problem: Customer reported intermittent power window failure and dashboard warning lights.
Diagnosis: Initial OBD scan revealed B1391 along with other codes. Visual inspection showed corrosion at BCM connections.
Solution: Replaced the body control module and cleaned all electrical connections.
Cost: $520 (including parts and labor)
Result: All electronic functions were restored, and the customer reported satisfaction with the repair.
Case Study 2: Wiring Repair on a 2016 Toyota Camry
Vehicle: 2016 Toyota Camry, 78,000 miles
Problem: Customer experienced malfunctioning locks and flickering lights.
Diagnosis: B1391 was triggered due to damaged wiring in the BCM harness.
Solution: Repaired the damaged wiring and secured all connections properly.
Cost: $180 (including parts and labor)
Result: The vehicle's electrical issues were resolved, and functionality was restored.