Quick Answer
U0790 means: U0790 indicates a communication error between vehicle control modules.
Can I drive with U0790? Immediate attention is recommended to avoid further damage.
Common Questions
What does U0790 mean and how does it affect my car?
The U0790 code suggests there's a communication problem between your vehicle's control modules. This can lead to various performance issues, such as erratic shifting and decreased fuel efficiency. If not addressed, it could result in more serious problems down the line.
What are the most common causes of U0790 and how much does it cost to fix?
Common causes include faulty control modules, damaged wiring, or software issues. Repair costs can range from $100 for simple wiring repairs to over $1,200 for control module replacements, depending on the severity of the issue.
Can I drive my car with U0790 or should I stop immediately?
Driving with a U0790 code is not advisable as it can lead to further damage. If you experience symptoms like harsh shifting or poor acceleration, it's best to stop driving and seek professional help.
How can I diagnose U0790 myself using GeekOBD APP?
Using the GeekOBD APP, you can perform an OBD2 scan to retrieve the U0790 code and any related codes. The app can also provide freeze frame data to help understand the fault context, guiding your next steps.
What vehicles are most commonly affected by U0790?
The U0790 code frequently affects models like the 2010-2017 Ford F-150 and the 2013-2018 Chevrolet Silverado, among others. It's wise to check for any manufacturer recalls or technical service bulletins (TSBs) related to this issue.
How can I prevent U0790 from happening again?
Regular maintenance is key. Ensure connections are clean and secure, keep an eye on wiring for signs of wear, and consider periodic software updates for your vehicle’s control modules to prevent glitches.
What is U0790?
DTC U0790 indicates a communication issue between the vehicle's control modules, specifically signaling that one module is not able to effectively communicate with another. This can result in various functional impairments across multiple systems, such as the transmission and engine control units. When this code is triggered, the affected vehicle may experience erratic behavior, which can include poor engine performance, irregular shifting in automatic transmissions, or even failure of certain electronic components. In simpler terms, think of your car's control modules as a team that needs to work together. If one member doesn't pass along critical information, it can disrupt the entire team's performance. For instance, if the engine control module (ECM) can't communicate with the transmission control module (TCM), you might notice that your vehicle shifts harshly or hesitates during acceleration. Owners of vehicles such as the Ford F-150 or Chevrolet Silverado should be particularly vigilant, as these models have been reported to frequently exhibit this code. Ignoring DTC U0790 can lead to more severe issues over time, such as reduced fuel efficiency and potential damage to the transmission or engine, ultimately leading to expensive repairs.
System: U - Network (Communication, CAN Bus)
Symptoms
Common symptoms when U0790 is present:
- Check engine light remains illuminated, indicating a fault in the vehicle's electronic systems.
- Engine may hesitate during acceleration, which can be frustrating during merging or passing.
- Transmission may exhibit harsh shifting, resulting in a less smooth driving experience.
- Increased fuel consumption, with reports of up to a 15% decrease in mileage due to inefficient operation.
- Dashboard warning lights may flicker or behave erratically, suggesting communication issues among modules.
Possible Causes
Most common causes of U0790 (ordered by frequency):
- The most common cause is a faulty control module (approximately 40% likelihood), where one of the electronic control units (ECUs) fails to communicate properly due to internal faults or software issues.
- Another frequent cause is damaged wiring or connectors (about 30% likelihood), where wear and tear lead to poor connections, disrupting communication between modules.
- A third possibility involves software glitches in the control module (20% likelihood); these can often be resolved through software updates or reprogramming, preventing future occurrences.
- Less common but serious causes include a failing powertrain control module (PCM); this can lead to catastrophic failures if not addressed promptly.
- A rare cause could be an issue with the vehicle's network wiring harness, where fraying or corrosion disrupts multiple connections, leading to widespread communication failures.
U0790 Repair Costs
Cost Breakdown by Repair Type
Control Module Replacement
Replacing a faulty control module often resolves the U0790 issue, but it requires proper programming.
- Total: $300 - $1,200
- Success rate: 85%
Wiring Repair
Repairing damaged wiring or connectors can directly resolve communication issues.
- Total: $100 - $500
- Success rate: 75%
Software Update
Updating the control module software can fix glitches causing communication errors.
- Total: $50 - $150
- Success rate: 70%
Money-Saving Tips for U0790
- 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 U0790 Diagnosis Process
Follow these systematic steps to accurately diagnose U0790. Each step builds on the previous one to ensure accurate diagnosis.
Step 1: Step 1: Initial visual inspection - Begin by checking for obvious signs like damaged wiring, loose connections, or corrosion
Step 1: Initial visual inspection - Begin by checking for obvious signs like damaged wiring, loose connections, or corrosion. This can take about 5-10 minutes.
Step 2: Step 2: OBD2 scan with GeekOBD APP - Use a diagnostic tool to retrieve all codes and freeze frame data, providing context for the U0790 code
Step 2: OBD2 scan with GeekOBD APP - Use a diagnostic tool to retrieve all codes and freeze frame data, providing context for the U0790 code. Expect this to take 10-15 minutes.
Step 3: Step 3: Component testing - Use a multimeter to test suspected components and ensure they are functioning as they should
Step 3: Component testing - Use a multimeter to test suspected components and ensure they are functioning as they should. This could require 20-30 minutes.
Step 4: Step 4: System function test - After any repairs, verify the proper operation of the affected systems and clear the codes to see if they return
Step 4: System function test - After any repairs, verify the proper operation of the affected systems and clear the codes to see if they return. This may take another 10-15 minutes.
Step 5: Step 5: Road test verification - Finally, take the vehicle for a drive under various conditions to confirm the success of the repair, which could take around 15-20 minutes
Step 5: Road test verification - Finally, take the vehicle for a drive under various conditions to confirm the success of the repair, which could take around 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: Control Module Replacement in 2015 Ford F-150
Vehicle: 2015 Ford F-150, 85,000 miles
Problem: Customer reported harsh shifting and check engine light illuminated.
Diagnosis: OBD2 scan revealed U0790 and confirmed faulty transmission control module.
Solution: Replaced the transmission control module and reprogrammed it to the vehicle's specifications.
Cost: $950 (parts: $600 for the module, $350 for labor)
Result: Customer reported smooth shifting and no recurrence of the check engine light.
Case Study 2: Wiring Repair in 2013 Chevrolet Silverado
Vehicle: 2013 Chevrolet Silverado, 70,000 miles
Problem: Check engine light on; vehicle hesitated during acceleration.
Diagnosis: Initial inspection revealed corrosion in the wiring harness connecting the ECM and TCM.
Solution: Repaired the damaged wiring and ensured all connectors were secure.
Cost: $300 (parts: $100 for wiring, $200 for labor)
Result: Resolved the issues, and the check engine light remained off post-repair.