WOMS
U code network Medium severity

U029E Lost Communication With NOX Sensor "B

The OBD2 code U029E indicates a loss of communication with the NOx (Nitrogen Oxide) sensor "B," which may affect the vehicle's emissions control system

Definition

The OBD2 code U029E indicates a loss of communication with the NOx (Nitrogen Oxide) sensor "B," which may affect the vehicle's emissions control system

Common causes

  • Faulty NOx sensor "B"
  • Damaged wiring or connectors
  • Poor electrical connections
  • Failed engine control module (ECM)
  • Corroded terminals
  • Software issues or updates needed
  • Blown fuse related to the NOx sensor circuit
  • Exhaust system leaks affecting sensor operation

Common misdiagnoses

  • Faulty NOX sensor
  • Wiring issues or damaged connectors
  • Faulty engine control module (ECM)
  • Issues with the exhaust system
  • Faulty turbocharger or related components
  • Problems with the fuel system
  • Incorrectly installed or malfunctioning EGR system
  • Software issues in the ECM
  • Other sensor failures (e.g., oxygen sensors)
  • Battery or power supply issues

Troubleshooting steps

  1. 1. Check for Other Codes

    Use an OBD-II scanner to check for any additional trouble codes. Sometimes, related codes can provide more context for the issue

  2. 2. Inspect Wiring and Connectors

    Visual Inspection: Check the wiring harness and connectors associated with the NOx sensor for any signs of damage, corrosion, or loose connections

  3. 3. Connector Pins

    Ensure that the pins in the connectors are not bent, corroded, or damaged

  4. 4. Test the NOx Sensor

    Resistance Check: If possible, measure the resistance of the NOx sensor to see if it falls within the manufacturer’s specifications

  5. 5. Voltage Check

    Check the voltage supply to the NOx sensor. Ensure that it is receiving the correct voltage as specified in the service manual

  6. 6. Check for Ground Issues

    Ensure that the NOx sensor has a good ground connection. A poor ground can lead to communication issues

  7. 7. Inspect the ECU

    Check the Engine Control Unit (ECU) for any signs of damage or corrosion. Ensure that the ECU is functioning properly and that there are no issues with its connectors

  8. 8. Perform a Communication Test

    Use a scan tool to perform a communication test with the NOx sensor. This can help determine if the sensor is communicating properly with the ECU

  9. 9. Check for Software Updates

    Sometimes, manufacturers release software updates for the ECU that can resolve communication issues. Check if there are any updates available for your vehicle

  10. 10. Clear Codes and Test Drive

    After performing the above checks and repairs, clear the trouble codes and take the vehicle for a test drive to see if the code returns

  11. 11. Replace the NOx Sensor

    If all other checks are satisfactory and the code persists, consider replacing the NOx sensor itself, as it may be faulty

  12. 12. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the NOx sensor or communication issues for your specific vehicle make and model. Manufacturers may have specific recommendations or known issues.1

  13. 13. Seek Professional Help

    If you are unable to resolve the issue after these steps, it may be best to consult a professional mechanic or technician who has experience with your vehicle’s specific systems. By following these steps, you should be able to identify the cause of the U029E code and take appropriate action to resolve the communication issue with the NOx sensor