Quick Answer
U0739 means: U0739 indicates a communication issue between the TCM and PCM, affecting vehicle performance.
Can I drive with U0739? Immediate diagnosis and repair are recommended to prevent further complications.
Common Questions
What does U0739 mean and how does it affect my car?
The U0739 code means your vehicle is experiencing a communication issue between the Transmission Control Module and the Powertrain Control Module. This can lead to erratic transmission behavior, poor fuel efficiency, and potential stalling. If left unresolved, it can further complicate your vehicle's performance and reliability, making it essential to diagnose and repair the issue promptly.
What are the most common causes of U0739 and how much does it cost to fix?
Common causes of U0739 include faulty wiring (60% likelihood), a malfunctioning TCM (25%), and software issues in the PCM (10%). Repair costs can range from $150 for wiring repairs to $1,200 for TCM replacement, depending on the nature of the issue and the parts needed.
Can I drive my car with U0739 or should I stop immediately?
While you might be able to drive your car with the U0739 code, it's advisable to stop and diagnose the issue as soon as possible. Continuing to drive could lead to further damage to the transmission and other components, potentially resulting in a more costly repair.
How can I diagnose U0739 myself using GeekOBD APP?
To diagnose U0739 with the GeekOBD APP, start by connecting the app to your vehicle's OBD2 port. Use the app to scan for DTCs, and check the freeze frame data for context. Look for any additional codes that may provide clues about the communication failure, and review the live data for the TCM and PCM to see if they are exchanging information effectively.
What vehicles are most commonly affected by U0739?
U0739 is frequently seen in vehicles like the 2015-2019 Ford F-150, 2016-2018 Chevrolet Silverado, and various models from Toyota and Nissan. These vehicles often come equipped with advanced transmission systems that can be sensitive to electrical issues.
How can I prevent U0739 from happening again?
To prevent U0739 from recurring, regularly inspect your vehicle’s wiring and connectors, especially in the transmission area. Ensure that your vehicle’s software is up-to-date and consider routine maintenance checks that include diagnostics to catch potential issues before they escalate.
What is U0739?
The diagnostic trouble code (DTC) U0739 indicates a communication error between the Transmission Control Module (TCM) and the Powertrain Control Module (PCM). This code often appears in vehicles equipped with advanced transmission systems, particularly in models such as the 2015-2019 Ford F-150 and the 2016-2018 Chevrolet Silverado. When the TCM and PCM cannot exchange crucial data, it can lead to various performance issues, including erratic shifting, poor fuel economy, and even stalling. This code typically suggests that there is a fault in the network communication, which could be due to faulty wiring, a malfunctioning module, or issues with the vehicle's onboard computer system. Failure to address this code promptly can result in more significant problems, including total transmission failure, which may lead to costly repairs. Car owners experiencing this code should be aware that it can lead to a reduction in vehicle reliability and safety, making regular diagnostics important to maintain optimal performance and avoid being stranded on the road.
System: U - Network (Communication, CAN Bus)
Symptoms
Common symptoms when U0739 is present:
- Check engine light stays on constantly, indicating a persistent issue that needs attention.
- Transmission may hesitate or shift roughly during acceleration, leading to a less smooth driving experience.
- Fuel economy decreased by 10-15%, which can significantly impact your vehicle's running costs.
- Loss of power during driving can occur, making it difficult to merge or overtake safely.
- The vehicle may enter 'limp mode', restricting speed and performance to protect the engine and transmission.
Possible Causes
Most common causes of U0739 (ordered by frequency):
- Faulty wiring or connections (60% likelihood) - Damaged or corroded wires can disrupt communication between modules.
- Malfunctioning TCM (25% likelihood) - A failed transmission control module may not send or receive signals correctly.
- Software issues in the PCM (10% likelihood) - Corrupted software can lead to communication failures between modules.
- Less common cause: Grounding issues can prevent proper electrical connections, affecting module communication.
- Rare but possible cause: A bad battery or alternator can cause voltage fluctuations, impacting the overall electrical system.
U0739 Repair Costs
Cost Breakdown by Repair Type
Wiring Repair
Repair or replace damaged wiring or connectors related to the TCM and PCM.
- Total: $150 - $400
- Success rate: 90%
TCM Replacement
Replace the faulty transmission control module.
- Total: $500 - $1,200
- Success rate: 95%
Software Update
Update the PCM software to fix potential bugs.
- Total: $100 - $200
- Success rate: 85%
Money-Saving Tips for U0739
- 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 U0739 Diagnosis Process
Follow these systematic steps to accurately diagnose U0739. Each step builds on the previous one to ensure accurate diagnosis.
Step 1: Step 1
Step 1: Initial visual inspection - Check for obvious signs like damaged wiring, loose connections, or corrosion (5-10 minutes)
Step 2: 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 3: Step 3
Step 3: Component testing - Use a multimeter or specific diagnostic tools to test suspected components (20-30 minutes)
Step 4: Step 4
Step 4: System function test - Verify proper operation after repairs and clear codes (10-15 minutes)
Step 5: Step 5
Step 5: Road test verification - Drive vehicle under various conditions to confirm repair success (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: Transmission Control Module Replacement on 2017 Ford F-150
Vehicle: 2017 Ford F-150, 85,000 miles
Problem: Customer complained of erratic shifting and a persistent check engine light.
Diagnosis: After scanning with the GeekOBD APP, the U0739 code was retrieved along with other transmission-related codes. A visual inspection revealed damaged wiring leading to the TCM.
Solution: Repaired the damaged wiring and replaced the TCM. Updated the vehicle software to ensure proper communication.
Cost: $800 (wiring repair: $200, TCM replacement: $600)
Result: Post-repair, the vehicle shifted smoothly, and the check engine light turned off.
Case Study 2: Wiring Repair on 2016 Chevrolet Silverado
Vehicle: 2016 Chevrolet Silverado, 60,000 miles
Problem: Customer reported poor fuel economy and stalling during acceleration.
Diagnosis: Diagnostic scan revealed U0739 alongside other codes. A thorough inspection indicated worn wiring harness.
Solution: Replaced the wiring harness and cleared all codes.
Cost: $250 (wiring repair)
Result: Improved fuel efficiency and resolved stalling issue. Customer was satisfied with the timely repair.