Quick Answer
B0379 means: DTC B0379 indicates a malfunction in the rear window defroster relay circuit.
Can I drive with B0379? This issue should be addressed promptly to ensure visibility and safety.
Common Questions
What does B0379 mean and how does it affect my car?
DTC B0379 indicates a problem with the rear window defroster relay circuit, which can hinder your rear visibility during cold or rainy conditions. If not addressed, it can lead to further electrical problems.
What are the most common causes of B0379 and how much does it cost to fix?
Common causes include a faulty defroster relay, damaged wiring, or corrosion. Repair costs range from $50 for a relay replacement to $300 for wiring repairs.
Can I drive my car with B0379 or should I stop immediately?
While it's possible to drive with this code, it's not advisable as it can impair your visibility. Addressing the issue promptly is crucial for safety.
How can I diagnose B0379 myself using GeekOBD APP?
Using the GeekOBD APP, you can scan for diagnostic codes, view freeze frame data for context, and perform live data monitoring to check the status of the defroster circuit.
What vehicles are most commonly affected by B0379?
Models like the 2015-2018 Honda Civic frequently experience this code, but it can also appear in various other makes and models with similar electrical systems.
How can I prevent B0379 from happening again?
Regularly inspecting electrical connections and ensuring that the defroster system is serviced can help prevent B0379 from recurring.
What is B0379?
DTC B0379 refers to an issue primarily related to the malfunction of the rear window defroster relay circuit. This trouble code indicates that the vehicle’s onboard diagnostics system has detected a fault within the circuitry associated with the rear window defroster. In practical terms, when this code appears, it often means that the rear defroster may not function properly, which could lead to visibility issues during cold weather or rainy conditions. If the rear window defroster is inoperable, it can create unsafe conditions by impairing the driver's ability to see clearly from the rear view, especially in adverse weather. Additionally, ignoring this code could lead to further electrical issues or even drain the vehicle's battery over time, as the system might attempt to operate without proper function. The code is typically found in models like the 2015-2018 Honda Civic, but it can also appear in other vehicles with similar electrical configurations. For vehicle owners, it's crucial to address this code promptly to ensure safety and reliability on the road.
System: B - Body (Airbags, Lighting, Security, Climate Control)
Symptoms
Common symptoms when B0379 is present:
- Check engine light stays on constantly, indicating that there is an ongoing issue that needs attention.
- Rear window defroster fails to heat up, leaving the driver unable to clear fog or ice from the rear window efficiently.
- Intermittent electrical issues, such as flickering lights or inconsistent operation of other electrical components, can occur if the problem worsens.
- Increased battery drain, as the circuit may draw power even when the vehicle is off, leading to a dead battery if not fixed.
- Possible malfunction of related components like the power windows, as electrical issues can often affect multiple systems.
Possible Causes
Most common causes of B0379 (ordered by frequency):
- The most common cause is a faulty rear window defroster relay, which accounts for about 60% of cases. This relay may have burned out or developed internal faults, disrupting the circuit.
- Another cause could be damaged wiring or connectors within the defroster circuit, leading to intermittent or complete loss of function. This is often due to wear and tear or exposure to moisture.
- Corrosion at the relay socket can also be a culprit, which can hinder proper electrical flow. Regular inspections can help prevent this issue from developing.
- In some cases, the vehicle's body control module may malfunction, leading to incorrect signals being sent to the rear defroster. This is less common but can be complex to diagnose.
- Rarely, issues with the vehicle's main fuse box can impact the rear defroster circuit, though this is typically accompanied by other electrical problems.
B0379 Repair Costs
Cost Breakdown by Repair Type
Replace Rear Window Defroster Relay
Replacing the faulty relay typically resolves the B0379 code.
- Total: $50 - $150
- Success rate: 90%
Repair Wiring Harness
Repairing damaged wiring or connectors can ensure proper electrical flow.
- Total: $100 - $300
- Success rate: 80%
Money-Saving Tips for B0379
- 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 B0379 Diagnosis Process
Follow these systematic steps to accurately diagnose B0379. 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 to test the defroster relay and wiring for continuity and proper function (20-30 minutes)
Step 3: Component testing - Use a multimeter to test the defroster relay and wiring for continuity and proper function (20-30 minutes).
Step 4: Step 4: System function test - After repairs, verify proper operation of the rear window defroster and clear codes from the ECU (10-15 minutes)
Step 4: System function test - After repairs, verify proper operation of the rear window defroster and clear codes from the ECU (10-15 minutes).
Step 5: Step 5: Road test verification - Drive the vehicle under various conditions to ensure the defroster operates correctly and the code does not reappear (15-20 minutes)
Step 5: Road test verification - Drive the vehicle under various conditions to ensure the defroster operates correctly and the code does not reappear (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: Rear Window Defroster Repair on 2017 Honda Civic
Vehicle: 2017 Honda Civic, 45,000 miles
Problem: Customer reported that the rear window defroster was inoperable.
Diagnosis: After scanning with GeekOBD, the B0379 code was confirmed. Inspection revealed a faulty defroster relay.
Solution: Replaced the rear window defroster relay and cleared the code.
Cost: $80 (including parts and labor)
Result: The rear defroster functioned normally after the repair, and the customer was satisfied.
Case Study 2: Wiring Issues in 2016 Toyota Corolla
Vehicle: 2016 Toyota Corolla, 30,000 miles
Problem: Customer experienced intermittent rear window defroster operation.
Diagnosis: Diagnostics showed B0379 code. Inspection found damaged wiring in the defroster circuit.
Solution: Repaired the damaged wiring and tested the system.
Cost: $150 (including parts and labor)
Result: The defroster now operates reliably, and the customer expressed appreciation for the thorough diagnosis.