Quick Answer
U0171 means: DTC U0171 signifies a communication failure between the engine control module and the transmission control module.
Can I drive with U0171? Immediate attention is recommended to prevent further transmission damage.
Common Questions
What does U0171 mean and how does it affect my car?
DTC U0171 indicates a communication failure between the engine control module and the transmission control module. This can lead to rough shifting, poor fuel economy, and even complete loss of power to the wheels. Addressing this code promptly ensures smooth operation and longevity of your vehicle's transmission.
What are the most common causes of U0171 and how much does it cost to fix?
Common causes include a faulty transmission control module, damaged wiring, or faulty sensors. Repair costs can range from $150 for wiring repairs to $1,200 for a complete module replacement, depending on the issue.
Can I drive my car with U0171 or should I stop immediately?
It's advisable to avoid driving your vehicle if you see this code. Continuing to drive can exacerbate transmission issues, leading to costly repairs. It's best to seek immediate assistance.
How can I diagnose U0171 myself using GeekOBD APP?
Using the GeekOBD APP, you can scan for DTCs and view freeze frame data. Look for related codes and monitor transmission performance parameters. This can provide insight into whether the TCM is functioning as it should.
What vehicles are most commonly affected by U0171?
This code is frequently found in 2015-2018 Ford Explorer and certain models of the Ford F-150. It's always advisable to check for any recalls or technical service bulletins related to your specific vehicle.
How can I prevent U0171 from happening again?
Regular maintenance, including checking wiring and connectors for wear, and keeping the vehicle's software updated can help prevent recurrence. Routine diagnostics using tools like the GeekOBD APP can also catch potential issues early.
What is U0171?
DTC U0171 indicates a communication issue between the vehicle’s engine control module (ECM) and the transmission control module (TCM). This trouble code suggests that the ECM is unable to receive data from the TCM, which could lead to significant performance issues. When the TCM is not functioning correctly, it may fail to send the proper signals for gear shifts, resulting in erratic transmission behavior. Drivers may experience harsh shifting, slipping, or even total loss of power to the wheels. The vehicle may enter 'limp mode,' limiting speed and acceleration to prevent further damage. Moreover, this code can trigger the check engine light, urging the driver to seek immediate repairs. It's crucial to address this code promptly, as ignoring it may lead to more severe transmission problems and costly repairs down the line. The TCM communicates with various sensors and actuators, so a fault in this code could also point to wiring issues or faulty connectors. Regular diagnostics and timely attention to symptoms associated with this trouble code can help preserve the longevity of your vehicle’s transmission system.
System: U - Network (Communication, CAN Bus)
Symptoms
Common symptoms when U0171 is present:
- Check engine light stays on constantly, indicating an unresolved issue that needs attention.
- Transmission may hesitate during acceleration, causing a delay or abrupt changes in speed.
- Fuel economy decreased by 10-15%, suggesting that the vehicle is not operating efficiently.
- Harsh shifting or slipping of gears can occur, leading to a frustrating driving experience.
- In severe cases, the vehicle may enter limp mode, limiting speed and making it unsafe to drive.
Possible Causes
Most common causes of U0171 (ordered by frequency):
- The most common cause is a faulty transmission control module, which accounts for approximately 40% of cases. This module may fail due to age or exposure to moisture.
- Another frequent issue is damaged wiring or connectors between the ECM and TCM, which can lead to intermittent communication failures.
- Faulty sensors related to transmission performance may also trigger this code. Regular inspections can prevent these failures.
- Less common causes include software issues within the TCM that may require a reprogramming or update.
- A rare but possible cause could be a complete failure of the engine control module itself, though this is less frequently encountered.
U0171 Repair Costs
Cost Breakdown by Repair Type
Transmission Control Module Replacement
Replacing the TCM to restore proper communication between the modules.
- Total: $600 - $1,200
- Success rate: 85%
Wiring Repair
Repairing or replacing damaged wiring or connectors.
- Total: $150 - $400
- Success rate: 90%
Software Update
Reprogramming the TCM software to correct potential bugs.
- Total: $100 - $200
- Success rate: 75%
Money-Saving Tips for U0171
- 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 U0171 Diagnosis Process
Follow these systematic steps to accurately diagnose U0171. Each step builds on the previous one to ensure accurate diagnosis.
Step 1: Step 1: Perform an initial visual inspection for damaged wiring, loose connections, or corrosion, which may take about 5-10 minutes
Step 1: Perform an initial visual inspection for damaged wiring, loose connections, or corrosion, which may take about 5-10 minutes.
Step 2: Step 2: Use an OBD2 scanner, like the GeekOBD APP, to retrieve all codes and freeze frame data to understand the fault context (10-15 minutes)
Step 2: Use an OBD2 scanner, like the GeekOBD APP, to retrieve all codes and freeze frame data to understand the fault context (10-15 minutes).
Step 3: Step 3: Conduct component testing with a multimeter or specialized diagnostic tools to check the functionality of suspected components (20-30 minutes)
Step 3: Conduct component testing with a multimeter or specialized diagnostic tools to check the functionality of suspected components (20-30 minutes).
Step 4: Step 4: Perform a system function test to verify proper operation after repairs and clear the codes (10-15 minutes)
Step 4: Perform a system function test to verify proper operation after repairs and clear the codes (10-15 minutes).
Step 5: Step 5: Conduct a road test under various conditions to confirm repair success and ensure that all systems function normally (15-20 minutes)
Step 5: Conduct a road test under various conditions to confirm repair success and ensure that all systems function normally (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: Ford Explorer 2017 - Transmission Control Module Replacement
Vehicle: 2017 Ford Explorer, 75,000 miles
Problem: Customer reported erratic shifting and check engine light illumination.
Diagnosis: After scanning with GeekOBD, U0171 was found along with other transmission-related codes. Visual inspection revealed corrosion in the TCM connector.
Solution: Replaced the transmission control module and repaired the wiring harness. Cleared codes and performed a road test.
Cost: $950 (including TCM and labor)
Result: Post-repair, the vehicle shifted smoothly, and the check engine light did not return.
Case Study 2: Ford F-150 2016 - Wiring Repair
Vehicle: 2016 Ford F-150, 60,000 miles
Problem: Driver experienced loss of power and harsh shifting.
Diagnosis: DTC U0171 was retrieved. Inspection showed frayed wires in the harness connecting the ECM and TCM.
Solution: Repaired the damaged wiring and secured all connections. Conducted software updates.
Cost: $300 (for wiring repairs and labor)
Result: The vehicle performed well after repairs, with no further issues reported.