WOMS
U code network Medium severity

U0019 Low Speed CAN Communication Bus

The OBD2 code U0019 indicates a problem with the low-speed CAN (Controller Area Network) communication bus, specifically that there is a communication issue between modules on the vehicle's network

Definition

The OBD2 code U0019 indicates a problem with the low-speed CAN (Controller Area Network) communication bus, specifically that there is a communication issue between modules on the vehicle's network

Common causes

  • Faulty CAN bus wiring or connectors
  • Short circuit in the CAN bus
  • Open circuit in the CAN bus
  • Faulty or damaged CAN bus module
  • Interference from other electrical components
  • Poor ground connections
  • Faulty or incompatible aftermarket accessories
  • Software issues or bugs in the vehicle's control modules
  • Low battery voltage or power supply issues
  • Corrosion or damage at the connectors

Common misdiagnoses

  • Faulty Engine Control Module (ECM)
  • Defective Body Control Module (BCM)
  • Bad wiring or connectors
  • Faulty sensors
  • Issues with the Transmission Control Module (TCM)
  • Low battery voltage
  • Faulty instrument cluster
  • Problems with the ABS module
  • Incorrectly diagnosed electrical issues
  • Software or firmware issues in modules

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. Addressing related codes can help in diagnosing the issue more effectively

  2. 2. Inspect Wiring and Connectors

    Visual Inspection: Check the wiring harnesses and connectors associated with the Low Speed CAN bus for any signs of damage, corrosion, or loose connections

  3. 3. Repair or Replace

    Repair any damaged wires or connectors and ensure all connections are secure

  4. 4. Test the CAN Bus

    Multimeter Test: Use a multimeter to check the voltage levels on the CAN bus wires. The typical voltage levels should be around 2.5V to 3.5V when the vehicle is on

  5. 5. Oscilloscope Test

    If available, use an oscilloscope to check the signal integrity on the CAN bus. Look for clean square wave signals without excessive noise

  6. 6. Check for Short Circuits

    Inspect the CAN bus wiring for any short circuits to ground or to other wires. This can cause communication failures

  7. 7. Inspect Modules

    Module Functionality: Check the functionality of the modules that communicate over the Low Speed CAN bus. A malfunctioning module can disrupt communication

  8. 8. Reprogram or Replace

    If a specific module is identified as faulty, consider reprogramming or replacing it

  9. 9. Check for Interference

    Ensure that there are no aftermarket devices or modifications that could be interfering with the CAN bus communication

  10. 10. Clear Codes and Test Drive

    After performing repairs, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns

  11. 11. Professional Diagnosis

    If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership with experience in diagnosing CAN bus issues

  12. 12. Check Battery and Ground Connections

    Ensure that the vehicle's battery is in good condition and that all ground connections are clean and secure, as poor power supply can affect module communication. By following these troubleshooting steps, you can systematically identify and resolve the issues related to the U0019 code