Quick Answer
C0399 means: C0399 indicates an ABS control module communication error, often affecting braking performance.
Can I drive with C0399? Immediate attention is recommended to ensure safe vehicle operation.
Common Questions
What does C0399 mean and how does it affect my car?
C0399 indicates an ABS control module communication error, which can severely impact braking performance. If this error occurs, you may notice the ABS warning light on your dashboard, and the braking system may not function correctly, increasing the risk of accidents.
What are the most common causes of C0399 and how much does it cost to fix?
Common causes of C0399 include a faulty ABS control module, damaged wiring, or poor connections. Repair costs can vary based on the specific issue, ranging from $100 for wiring repairs to $700 for a control module replacement.
Can I drive my car with C0399 or should I stop immediately?
It's not advisable to drive with C0399, as it can compromise your braking system. If the ABS light is on, you should have your vehicle inspected as soon as possible to ensure your safety.
How can I diagnose C0399 myself using GeekOBD APP?
You can use the GeekOBD APP to scan for DTCs, check freeze frame data for context, and monitor real-time data from the ABS system. This will help you identify issues and determine whether it's a wiring, module, or connection problem.
What vehicles are most commonly affected by C0399?
Models like the Ford F-150 (2011-2019) and Chevrolet Silverado (2014-2019) frequently experience C0399. Owners of these vehicles should be vigilant about brake system checks, especially if they notice any unusual symptoms.
How can I prevent C0399 from happening again?
Regular vehicle maintenance, including inspecting electrical connections and the ABS system, can help prevent C0399. Ensuring that your vehicle is clean and free of corrosion and moisture can also mitigate risks.
What is C0399?
The DTC C0399 code indicates a communication error between the ABS (Anti-lock Braking System) control module and the vehicle’s other control modules. This code typically surfaces in vehicles such as the Ford F-150 (2011-2019) and Chevrolet Silverado (2014-2019). When the ABS control module cannot communicate with the vehicle’s engine control unit (ECU), it can lead to a host of braking issues, including the inability of the anti-lock system to function properly. Car owners might notice a warning light on the dashboard or experience abnormal braking behavior, such as the brakes locking up or not engaging when needed. This can pose serious safety risks, especially in emergency braking situations. The root cause of this issue can vary, from a faulty ABS control module to damaged wiring or poor connections. If you see this code, it’s crucial to address it promptly, as ignoring it could lead to further damage to the vehicle’s braking system, which is critical for safe driving. Regular system checks, especially if your vehicle has been exposed to harsh weather or rough terrain, can help catch these issues early.
System: C - Chassis (ABS, Steering, Suspension)
Symptoms
Common symptoms when C0399 is present:
- The ABS warning light illuminates on the dashboard, indicating a potential issue with the braking system.
- Braking performance is erratic, with the brakes either locking up or failing to engage properly during sudden stops.
- Vehicle stability control may be compromised, causing difficulty in handling, particularly in wet or slippery conditions.
- Unusual noise from the braking system, including grinding or squeaking, which may signal further mechanical issues.
- Increased stopping distance, making the vehicle feel less responsive when applying brakes, which can be alarming during emergency maneuvers.
Possible Causes
Most common causes of C0399 (ordered by frequency):
- The most common cause is a faulty ABS control module, occurring in about 40% of cases. This part can fail due to electrical issues or manufacturing defects.
- Damaged or corroded wiring harnesses account for around 25% of issues, particularly in older models or vehicles that have experienced harsh weather.
- Poor connections at the ABS module or other control modules can cause intermittent communication failures, often due to loose or burnt connectors.
- Less common but serious causes include a malfunctioning ECU, which can lead to multiple DTCs being triggered and requires in-depth diagnostics.
- Rarely, software glitches in the vehicle’s firmware can cause communication errors, which may require a software update from the manufacturer.
C0399 Repair Costs
Cost Breakdown by Repair Type
ABS Control Module Replacement
Replacing the faulty ABS control module with a new or refurbished unit.
- Total: $300 - $700
- Success rate: 85%
Wiring Repair
Fixing or replacing the damaged wiring or connectors leading to the ABS module.
- Total: $100 - $300
- Success rate: 75%
Money-Saving Tips for C0399
- 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 C0399 Diagnosis Process
Follow these systematic steps to accurately diagnose C0399. Each step builds on the previous one to ensure accurate diagnosis.
Step 1: Step 1: Initial visual inspection - Check the ABS control module and wiring for visible damage, corrosion, or loose connections (5-10 minutes)
Step 1: Initial visual inspection - Check the ABS control module and wiring for visible damage, corrosion, or loose connections (5-10 minutes).
Step 2: Step 2: OBD2 scan with GeekOBD APP - Use the app to retrieve all stored codes and freeze frame data for context (10-15 minutes)
Step 2: OBD2 scan with GeekOBD APP - Use the app to retrieve all stored codes and freeze frame data for context (10-15 minutes).
Step 3: Step 3: Component testing - Test the ABS control module and related wiring with a multimeter to check for continuity and proper voltage (20-30 minutes)
Step 3: Component testing - Test the ABS control module and related wiring with a multimeter to check for continuity and proper voltage (20-30 minutes).
Step 4: Step 4: System function test - Restore connections and verify the ABS system is functioning as intended after repairs (10-15 minutes)
Step 4: System function test - Restore connections and verify the ABS system is functioning as intended after repairs (10-15 minutes).
Step 5: Step 5: Road test verification - Drive the vehicle under various conditions to ensure the ABS and braking system operate correctly (15-20 minutes)
Step 5: Road test verification - Drive the vehicle under various conditions to ensure the ABS and braking system operate correctly (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: ABS Control Module Replacement in 2017 Ford F-150
Vehicle: 2017 Ford F-150, 55,000 miles
Problem: Customer reported ABS warning light on dashboard and erratic braking.
Diagnosis: Diagnostic scan revealed C0399; further inspection found a faulty ABS control module.
Solution: Replaced the ABS control module and cleared the DTC, confirming functionality.
Cost: $600 (parts: $500 for module, $100 labor)
Result: Braking issues resolved and ABS warning light extinguished after successful repair.
Case Study 2: Wiring Repair in 2015 Chevrolet Silverado
Vehicle: 2015 Chevrolet Silverado, 70,000 miles
Problem: Owner experienced ABS light on and noticed brakes locking up intermittently.
Diagnosis: Found loose connectors and damaged wiring leading to the ABS module.
Solution: Repaired wiring and secured all connections, followed by a system test.
Cost: $200 (parts: $50 for connectors, $150 labor)
Result: ABS system functioned correctly post-repair, and warning lights cleared.