U0959 - Communication Issue in Multiple Modules for 2015-2019 GM Vehicles

Quick Answer

U0959 means: U0959 indicates a communication failure between vehicle control modules.

Fix: Check and replace faulty components Cost: $100 - $300 Time: 90-180 minutes

Can I drive with U0959? Immediate attention required to ensure vehicle safety and functionality.

Common Questions

What does U0959 mean and how does it affect my car?

U0959 indicates a communication issue between multiple control modules in your vehicle, which can lead to malfunctioning electronic systems, such as engine performance and safety features. If not addressed, it can result in more severe problems and costly repairs in the long run.

What are the most common causes of U0959 and how much does it cost to fix?

Common causes include damaged wiring, malfunctioning control modules, and poor connections. Repair costs can range from $50 for simple connector cleaning to over $800 for replacing a faulty control module.

Can I drive my car with U0959 or should I stop immediately?

It’s advised not to drive your vehicle extensively with the U0959 code present, as it may compromise critical systems. If the issue is severe, it could result in stalling or failure of important safety features.

How can I diagnose U0959 myself using GeekOBD APP?

Using the GeekOBD APP, you can perform a full OBD2 scan to retrieve all diagnostic trouble codes. Pay attention to freeze frame data as it provides context to the U0959 code, allowing you to identify when and how the issue occurs.

What vehicles are most commonly affected by U0959?

U0959 is commonly found in 2015-2019 Chevrolet, GMC, and Cadillac models, including the Silverado, Sierra, and Escalade. Many of these vehicles may have associated recalls or Technical Service Bulletins (TSBs) related to communication issues.

How can I prevent U0959 from happening again?

Regular vehicle maintenance, including checking wiring harnesses and connectors, can help prevent future occurrences of U0959. Additionally, keeping your vehicle’s software up to date and avoiding aftermarket modifications can reduce risks.

What is U0959?

The OBD-II Diagnostic Trouble Code (DTC) U0959 indicates a communication failure between two or more control modules in vehicles, particularly affecting General Motors (GM) models manufactured between 2015 and 2019. This code is often associated with issues in the vehicle's communication network, which is critical for various systems to function properly, including the engine control unit (ECU), transmission control module (TCM), and body control module (BCM). When the U0959 code is triggered, it means that a specific module is unable to receive or send messages to other modules, leading to potential failures in critical vehicle functions such as engine performance, safety features, and electronic stability control. For example, you might notice that your vehicle's dashboard lights behave erratically, or certain features like cruise control or automatic braking may become non-operational. Ignoring this code can lead to further complications, potentially resulting in costly repairs down the line. It’s essential to address U0959 promptly to ensure your vehicle's safety and reliability.

System: U - Network (Communication, CAN Bus)

Symptoms

Common symptoms when U0959 is present:

  • The check engine light remains illuminated continuously, indicating an underlying issue that requires attention.
  • You may experience erratic behavior of dashboard lights, with some lights flickering or staying on even when the vehicle is off.
  • Certain electronic features, such as cruise control and traction control, may become non-responsive or fail to activate.
  • The vehicle may exhibit poor acceleration or shifting issues due to communication failures between the engine and transmission modules.
  • In some cases, drivers report that their vehicle experiences intermittent stalling or rough idling.

Possible Causes

Most common causes of U0959 (ordered by frequency):

  1. The most common cause of U0959 is damaged or corroded wiring in the communication network, which has a likelihood of about 60%. Inspecting wiring harnesses is crucial.
  2. A second frequent cause is a malfunctioning control module, which may fail to send or receive data properly. This could happen due to software issues or internal faults.
  3. Thirdly, poor connections at the module connectors, which can prevent proper communication, is another potential cause. Regular maintenance checks on connectors can help prevent this.
  4. Less commonly, a failing battery or alternator can lead to insufficient power supply to control modules, causing communication errors.
  5. In rare cases, aftermarket modifications such as alarm systems or stereo installations can disrupt the vehicle's communication network.

U0959 Repair Costs

Cost Breakdown by Repair Type

Wiring Repair

Repairing or replacing damaged wiring in the communication network.

  • Total: $100 - $300
  • Success rate: 85%
Control Module Replacement

Replacing a faulty control module that is preventing communication.

  • Total: $400 - $800
  • Success rate: 90%
Connector Cleaning and Tightening

Cleaning and securing loose connectors to ensure proper communication.

  • Total: $50 - $150
  • Success rate: 75%
Money-Saving Tips for U0959
  • 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 U0959 Diagnosis Process

Follow these systematic steps to accurately diagnose U0959. Each step builds on the previous one to ensure accurate diagnosis.

Step 1: Step 1: Initial visual inspection - Check for damaged wiring, loose connections, or corrosion on control module connectors (5-10 minutes)

Step 1: Initial visual inspection - Check for damaged wiring, loose connections, or corrosion on control module connectors (5-10 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 2: Step 2: OBD2 scan with GeekOBD APP - Use the app to retrieve all codes and freeze frame data to understand the context of the fault (10-15 minutes)

Step 2: OBD2 scan with GeekOBD APP - Use the app to retrieve all codes and freeze frame data to understand the context of the fault (10-15 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 3: Step 3: Component testing - Utilize a multimeter to test suspected components and connectors for continuity and proper voltage (20-30 minutes)

Step 3: Component testing - Utilize a multimeter to test suspected components and connectors for continuity and proper voltage (20-30 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 4: Step 4: System function test - After making repairs, verify the proper operation of affected systems and clear codes (10-15 minutes)

Step 4: System function test - After making repairs, verify the proper operation of affected systems and clear codes (10-15 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.
Step 5: Step 5: Road test verification - Drive the vehicle under various conditions to confirm that all systems are functioning correctly and that the U0959 code does not return (15-20 minutes)

Step 5: Road test verification - Drive the vehicle under various conditions to confirm that all systems are functioning correctly and that the U0959 code does not return (15-20 minutes).

GeekOBD APP Tip: Use GeekOBD APP to monitor real-time data during this diagnostic step for accurate results and professional-grade analysis.

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: 2017 Chevrolet Silverado 1500 - Communication Failure

Vehicle: 2017 Chevrolet Silverado 1500, 45,000 miles

Problem: Customer reported the check engine light was on, and cruise control was inoperable.

Diagnosis: After a thorough scan with GeekOBD APP, U0959 was revealed. Inspection showed corroded wiring.

Solution: Replaced the corroded wiring and secured all connectors.

Cost: $250 (wiring repair and labor included)

Result: The vehicle's systems were restored, and the check engine light was cleared.

Case Study 2: 2018 GMC Sierra 2500 - Control Module Replacement

Vehicle: 2018 GMC Sierra 2500, 30,000 miles

Problem: Customer noticed intermittent stalling and dashboard warning lights.

Diagnosis: Diagnostic check revealed U0959 and further testing identified a faulty body control module.

Solution: Replaced the body control module and updated the software.

Cost: $650 (module replacement and programming included)

Result: The stalling issue was resolved, and all systems functioned normally after the repair.

Diagnose U0959

Use GeekOBD APP for professional diagnosis!

  • Real-time data monitoring
  • Advanced diagnostic features
  • Step-by-step repair guidance
  • Professional-grade analysis
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Code Information

Code: U0959
System: Network (Communication, CAN Bus)
Severity: HIGH
Category: Network Codes