Quick Answer
C0739 means: C0739 refers to a vehicle speed sensor circuit performance issue.
Can I drive with C0739? Immediate attention is recommended to avoid safety risks and further vehicle damage.
Common Questions
What does C0739 mean and how does it affect my car?
C0739 indicates a problem with your vehicle speed sensor circuit. This can affect how your car shifts gears, potentially leading to rough driving experiences. If unaddressed, it can also impact fuel efficiency and overall safety.
What are the most common causes of C0739 and how much does it cost to fix?
The most common causes include a faulty vehicle speed sensor, which can cost between $150 and $300 to replace. Wiring issues can be repaired for about $100 to $200, while ECU problems can range from $300 to $800.
Can I drive my car with C0739 or should I stop immediately?
It's not advisable to drive your vehicle with a C0739 code. Ignoring this issue can lead to transmission problems and reduced safety features like ABS functionality.
How can I diagnose C0739 myself using GeekOBD APP?
Using the GeekOBD APP, you can scan for DTCs, view live data, and check the performance of the vehicle speed sensor. This will help you identify if the sensor or wiring is faulty.
What vehicles are most commonly affected by C0739?
Commonly affected vehicles include the 2010-2015 Ford Fusion and 2011-2014 Chevrolet Malibu, among others. Always check for any known recalls or service bulletins related to your specific model.
How can I prevent C0739 from happening again?
Regular maintenance, including wiring checks and sensor inspections, can help prevent the C0739 code. Additionally, ensure that any repairs are performed by qualified professionals to maintain system integrity.
What is C0739?
DTC C0739 indicates a problem within the vehicle speed sensor circuit. This diagnostic trouble code (DTC) typically appears in vehicles equipped with an electronic control unit (ECU) that monitors the input from the vehicle speed sensor (VSS). The VSS provides crucial data regarding the speed of the vehicle, which is essential for various systems including transmission control, traction control, and ABS (Anti-lock Braking System). When the ECU detects that the input from the VSS is outside of expected parameters, it triggers the C0739 code. This could stem from issues like a faulty sensor, wiring problems, or even a malfunctioning ECU. The implications of this code can be significant, as poor speed readings can affect gear shifting, fuel efficiency, and overall vehicle performance. It's important for car owners to address this code promptly, as it can lead to further complications, such as transmission problems or reduced safety features due to the ABS not functioning properly. Commonly seen in models like 2010-2015 Ford Fusion and 2011-2014 Chevrolet Malibu, the C0739 code requires careful diagnosis and repair to ensure safe vehicle operation.
System: C - Chassis (ABS, Steering, Suspension)
Symptoms
Common symptoms when C0739 is present:
- Check engine light stays on constantly, which can indicate a persistent issue that needs attention.
- Transmission shifts roughly or unpredictably, causing a jerky driving experience that may lead to further transmission wear.
- Speedometer may read inaccurately or fluctuate wildly, making it difficult to gauge actual vehicle speed.
- Fuel economy decreases significantly, often by 10-20%, due to improper gear shifts and engine management.
- ABS warning light may illuminate, indicating that the vehicle's traction and braking systems are compromised.
Possible Causes
Most common causes of C0739 (ordered by frequency):
- Faulty Vehicle Speed Sensor (VSS) - This is the most common cause, accounting for about 60% of cases. The sensor may wear out or fail, sending incorrect signals to the ECU.
- Wiring Issues - Damaged or corroded wiring can disrupt the signal from the VSS to the ECU, leading to a C0739 code. This accounts for approximately 25% of the cases.
- Faulty ECU - A malfunctioning ECU can misinterpret signals from the VSS, causing the code to appear even if the sensor is functioning properly. This is less common but can occur in about 10% of cases.
- Mechanical Issues - Problems with the transmission or speedometer gears can also trigger this code, though they are less frequent causes.
- Environmental Factors - Issues like water intrusion or dirt affecting the sensor can lead to intermittent faults, making it a rare cause.
C0739 Repair Costs
Cost Breakdown by Repair Type
VSS Replacement
Replacing the faulty vehicle speed sensor with a new part.
- Total: $150 - $300
- Success rate: 90%
Wiring Repair
Repairing or replacing damaged wiring in the VSS circuit.
- Total: $100 - $200
- Success rate: 85%
ECU Reprogramming
Reprogramming or replacing the vehicle's ECU if it is malfunctioning.
- Total: $300 - $800
- Success rate: 75%
Money-Saving Tips for C0739
- 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 C0739 Diagnosis Process
Follow these systematic steps to accurately diagnose C0739. 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 or specific diagnostic tools to test the VSS and wiring harness for continuity and voltage levels (20-30 minutes)
Step 3: Component testing - Use a multimeter or specific diagnostic tools to test the VSS and wiring harness for continuity and voltage levels (20-30 minutes).
Step 4: Step 4: System function test - Verify the operation of the VSS by monitoring live data through the GeekOBD APP to ensure it reports accurate speed (10-15 minutes)
Step 4: System function test - Verify the operation of the VSS by monitoring live data through the GeekOBD APP to ensure it reports accurate speed (10-15 minutes).
Step 5: Step 5: Road test verification - Drive the vehicle under various conditions to confirm repair success and clear codes (15-20 minutes)
Step 5: Road test verification - Drive the vehicle under various conditions to confirm repair success and clear codes (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: 2014 Ford Fusion Speed Sensor Replacement
Vehicle: 2014 Ford Fusion, 85,000 miles
Problem: Customer reported the check engine light and erratic speedometer readings.
Diagnosis: Initial scan revealed code C0739. Further testing confirmed a faulty vehicle speed sensor.
Solution: Replaced the vehicle speed sensor and cleared the error codes.
Cost: $220 (including parts and labor)
Result: Customer reported improved driving experience and accurate speed readings post-repair.
Case Study 2: 2012 Chevrolet Malibu Wiring Repair
Vehicle: 2012 Chevrolet Malibu, 90,000 miles
Problem: Customer experienced transmission shifting issues and check engine light.
Diagnosis: C0739 was present. Inspection revealed damaged wiring in the speed sensor circuit.
Solution: Repaired the wiring and secured the connections.
Cost: $150 (cost of parts and labor)
Result: Transmission shifting returned to normal; no further codes appeared.