WOMS
U code network High severity

U0070 Vehicle Communication Bus E (-) Low

The OBD2 code U0070 indicates a communication issue within the vehicle's communication bus, specifically that the Vehicle Communication Bus E is experiencing a low signal or malfunction

Definition

The OBD2 code U0070 indicates a communication issue within the vehicle's communication bus, specifically that the Vehicle Communication Bus E is experiencing a low signal or malfunction

Common causes

  • Faulty communication module
  • Damaged wiring or connectors
  • Short circuit in the communication bus
  • Open circuit in the communication bus
  • Faulty control module
  • Poor ground connection
  • Interference from aftermarket devices
  • Software issues or bugs in the modules

Common misdiagnoses

  • Faulty Engine Control Module (ECM)
  • Defective Body Control Module (BCM)
  • Bad wiring or connectors in the communication bus
  • Malfunctioning Transmission Control Module (TCM)
  • Issues with the Powertrain Control Module (PCM)
  • Faulty sensors or actuators
  • Battery or charging system problems
  • Software or firmware issues in modules
  • Grounding issues in the vehicle's electrical system
  • Incorrectly installed aftermarket accessories or devices

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. Other codes can provide context and help identify the root cause of the issue

  2. 2. Inspect Wiring and Connectors

    Visually inspect the wiring and connectors associated with the communication bus. Look for signs of damage, corrosion, or loose connections

  3. 3. Pay special attention to the connectors for the modules that communicate over bus E

  4. 4. Check for Short Circuits or Open Circuits

    Use a multimeter to check for continuity in the communication lines. Look for any short circuits to ground or open circuits that could disrupt communication

  5. 5. Test the Modules

    Identify the modules that communicate over bus E. Check if they are functioning properly. If a specific module is malfunctioning, it may cause communication issues

  6. 6. If possible, perform a module reset or reprogramming

  7. 7. Inspect the Ground Connections

    Ensure that all ground connections related to the communication bus are secure and free of corrosion. Poor grounding can lead to communication issues

  8. 8. Check for Interference

    Look for any aftermarket devices or modifications that may interfere with the communication bus. This includes alarms, stereo systems, or other electronic devices

  9. 9. Scan for Software Updates

    Check if there are any software updates available for the vehicle’s modules. Sometimes, manufacturers release updates to fix communication issues

  10. 10. Perform a Battery Reset

    Disconnect the vehicle's battery for a few minutes to reset the modules. Reconnect and see if the code reappears

  11. 11. Consult Technical Service Bulletins (TSBs)

    Look for any TSBs related to the specific make and model of the vehicle. Manufacturers may have documented known issues and solutions

  12. 12. Seek Professional Help

    If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who has experience with vehicle communication systems.Conclusion Troubleshooting a U0070 code can be complex due to the nature of vehicle communication systems. It’s important to approach the diagnosis methodically and to ensure that all potential causes are considered. If you're not comfortable performing these steps, it's advisable to seek assistance from a qualified technician