B0399 - Fuel Level Sensor Range/Performance Problem in Honda and Toyota Models

Quick Answer

B0399 means: DTC B0399 indicates a malfunction in the fuel level sensor range or performance.

Fix: Check and replace faulty components Cost: $150 - $300 Time: 90-180 minutes

Can I drive with B0399? Immediate diagnosis is recommended to avoid running out of fuel unexpectedly.

Common Questions

What does B0399 mean and how does it affect my car?

DTC B0399 signifies a problem with the fuel level sensor, which could lead to incorrect fuel readings. This can cause your vehicle to stall unexpectedly or maintain poor fuel economy, affecting your daily driving experience.

What are the most common causes of B0399 and how much does it cost to fix?

Common causes of B0399 include a faulty fuel level sensor and damaged wiring. Repair costs typically range from $150 to $300 for sensor replacement, depending on your vehicle model and labor rates.

Can I drive my car with B0399 or should I stop immediately?

While you may still be able to drive your vehicle, it is advisable to address the B0399 code as soon as possible to avoid running out of fuel unexpectedly or suffering from reduced engine performance.

How can I diagnose B0399 myself using GeekOBD APP?

Using the GeekOBD APP, you can scan for codes, view real-time data from the fuel level sensor, and analyze freeze frame data to understand the conditions leading to the B0399 code.

What vehicles are most commonly affected by B0399?

DTC B0399 is frequently reported in 2015-2020 Honda Civics and Toyota Corollas. Always check for any recalls or Technical Service Bulletins (TSBs) related to fuel system issues.

How can I prevent B0399 from happening again?

Regular maintenance, including fuel system inspections and keeping your fuel tank at least a quarter full, can help prevent issues with the fuel level sensor and related components.

What is B0399?

DTC B0399 indicates a fuel level sensor range or performance problem, often affecting vehicles from manufacturers like Honda and Toyota, particularly models produced between 2015 and 2020. This code typically arises when the Engine Control Module (ECM) detects that the fuel level sensor's readings are outside of the expected range, suggesting that the sensor may be malfunctioning or there is an issue in the circuit connecting the sensor to the ECM. This problem can lead to inaccurate fuel level readings on your dashboard, which in turn can affect fuel management and lead to unexpected vehicle behavior such as stalling or reduced acceleration. Additionally, if the fuel gauge constantly shows empty or full, it can create anxiety for drivers unsure of their actual fuel levels. Ignoring this code can lead to further engine performance issues and potential damage. For example, if a driver mistakenly believes they have enough fuel when they do not, they could run out of gas, leading to vehicle breakdowns. Prompt diagnosis and repair are crucial to maintain vehicle efficiency and performance.

System: B - Body (Airbags, Lighting, Security, Climate Control)

Symptoms

Common symptoms when B0399 is present:

  • The check engine light is illuminated, indicating an underlying issue that needs attention.
  • The fuel gauge is inaccurate, often displaying empty or full regardless of the actual fuel level, leading to confusion while driving.
  • The vehicle may experience stalling or hesitation during acceleration, particularly when fuel levels are low.
  • Fuel economy may decrease significantly, leading to an increase in refueling frequency, which may be noticeable in your monthly budget.
  • You might notice that the vehicle struggles to start if the fuel level sensor is not providing accurate data to the fuel system.

Possible Causes

Most common causes of B0399 (ordered by frequency):

  1. The most common cause of B0399 is a faulty fuel level sensor, which can occur in about 70% of cases, often due to wear and tear or exposure to fuel over time.
  2. Another cause could be corroded or damaged wiring in the fuel level sensor circuit, leading to poor connectivity and inaccurate readings.
  3. A malfunctioning ECM may misinterpret the signals from the fuel level sensor, leading to false codes. Keeping the ECM updated with the latest software can help prevent this.
  4. Less common but more serious causes include a defective fuel pump assembly, which can lead to fuel delivery issues and requires immediate attention.
  5. In rare instances, a software glitch in the vehicle's onboard computer can trigger a false B0399 code, which may necessitate a reset or reprogramming.

B0399 Repair Costs

Cost Breakdown by Repair Type

Fuel Level Sensor Replacement

Replacing the faulty fuel level sensor with an OEM part to ensure proper fit and function.

  • Total: $150 - $300
  • Success rate: 85%
ECM Reprogramming

Updating or reprogramming the vehicle's ECM to resolve software-related issues.

  • Total: $100 - $200
  • Success rate: 70%
Money-Saving Tips for B0399
  • 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 B0399 Diagnosis Process

Follow these systematic steps to accurately diagnose B0399. 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 on the fuel level sensor (5-10 minutes)

Step 1: Initial visual inspection - Check for obvious signs like damaged wiring, loose connections, or corrosion on the fuel level sensor (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 and how the vehicle was performing when the code was triggered (10-15 minutes)

Step 2: OBD2 scan with GeekOBD APP - Retrieve all codes and freeze frame data to understand the fault context and how the vehicle was performing when the code was triggered (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 a multimeter to test the fuel level sensor for continuity and proper voltage, ensuring it's within specifications (20-30 minutes)

Step 3: Component testing - Use a multimeter to test the fuel level sensor for continuity and proper voltage, ensuring it's within specifications (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 - After any repairs, verify the proper operation of the fuel level sensor and clear codes to reset the system (10-15 minutes)

Step 4: System function test - After any repairs, verify the proper operation of the fuel level sensor and clear codes to reset the system (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 the vehicle under various conditions to confirm that the fuel gauge works correctly and that no new codes appear (15-20 minutes)

Step 5: Road test verification - Drive the vehicle under various conditions to confirm that the fuel gauge works correctly and that no new codes appear (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: Fuel Level Sensor Replacement in a 2017 Honda Civic

Vehicle: 2017 Honda Civic, 45,000 miles

Problem: Customer reported that the fuel gauge remained stuck on full, causing anxiety about fuel levels.

Diagnosis: After using the GeekOBD APP, B0399 was confirmed. A visual inspection revealed corroded wiring.

Solution: Replaced the fuel level sensor and repaired the wiring harness.

Cost: $220 (sensor $150, labor $70)

Result: The fuel gauge functioned properly post-repair, and the customer was satisfied.

Case Study 2: ECM Reprogramming for a 2018 Toyota Corolla

Vehicle: 2018 Toyota Corolla, 30,000 miles

Problem: Customer experienced erratic fuel gauge readings and received a B0399 code.

Diagnosis: Diagnostic steps confirmed a faulty signal from the sensor, but the wiring was intact.

Solution: Reprogrammed the ECM, resolving the issue without replacing any hardware.

Cost: $150 (labor only)

Result: The fuel gauge returned to normal operation, and the customer reported no further issues.

Diagnose B0399

Use GeekOBD APP for professional diagnosis!

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  • Step-by-step repair guidance
  • Professional-grade analysis
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Code Information

Code: B0399
System: Body (Airbags, Lighting, Security, Climate Control)
Severity: HIGH
Category: Body Codes