WOMS
U code network High severity

U011B Lost Communication With Rocker Arm Control Module "A

The OBD2 code U011B indicates a loss of communication with the Rocker Arm Control Module "A," suggesting that the vehicle's control module is unable to receive or send data to this specific component

Definition

The OBD2 code U011B indicates a loss of communication with the Rocker Arm Control Module "A," suggesting that the vehicle's control module is unable to receive or send data to this specific component

Common causes

  • Faulty rocker arm control module
  • Wiring issues (damaged, frayed, or corroded wires)
  • Poor connections or loose connectors
  • Faulty engine control module (ECM)
  • Software issues or programming errors
  • Blown fuses
  • Electrical interference or shorts in the circuit
  • Battery or power supply issues

Common misdiagnoses

  • Faulty wiring or connectors
  • Defective Engine Control Module (ECM)
  • Malfunctioning Variable Valve Timing (VVT) system
  • Issues with the camshaft or crankshaft position sensors
  • Problems with the powertrain control module (PCM)
  • Incorrectly calibrated or programmed modules
  • Faulty rocker arm control module
  • Low engine oil pressure or oil flow issues

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide more context and help identify related issues

  2. 2. Inspect Wiring and Connectors

    Visual Inspection: Check the wiring harness and connectors associated with the rocker arm control module. Look for signs of damage, corrosion, or loose connections

  3. 3. Connector Pins

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

  4. 4. Test the Rocker Arm Control Module

    If accessible, test the rocker arm control module for proper operation. This may involve checking the module's power and ground circuits

  5. 5. Use a multimeter to measure voltage and ground at the module's connector

  6. 6. Check for Communication Issues

    Use a scan tool to check if the rocker arm control module is communicating with the Engine Control Module (ECM) and other modules

  7. 7. If the module is not responding, it may be faulty or there may be a communication issue in the network

  8. 8. Inspect the CAN Bus

    The U011B code may be related to issues in the Controller Area Network (CAN) bus. Check for shorts, opens, or faults in the CAN wiring

  9. 9. Use an oscilloscope or a CAN bus tester to monitor the communication signals on the bus

  10. 10. Check Power and Ground

    Ensure that the rocker arm control module is receiving the correct voltage and has a good ground connection

  11. 11. If there are issues with power or ground, trace the wiring back to the source

  12. 12. Perform a Module Reset

    Sometimes, resetting the modules can clear temporary communication issues. Disconnect the battery for a few minutes, then reconnect it and check for codes again

  13. 13. Update Software/Firmware

    Check if there are any software updates available for the vehicle’s ECM or the rocker arm control module. Sometimes, communication issues can be resolved with an update

  14. 14. Replace the Rocker Arm Control Module

    If all other steps have been exhausted and the module is still not communicating, it may be necessary to replace the rocker arm control module

  15. 15. Consult Technical Service Bulletins (TSBs)

    Look for any TSBs related to the U011B code or the rocker arm control module for your specific vehicle make and model. Manufacturers may have specific recommendations or known issues.1

  16. 16. Seek Professional Help

    If you are unable to resolve the issue, consider seeking help from a professional mechanic or dealership, especially if specialized diagnostic equipment is needed. By following these steps, you should be able to identify the root cause of the U011B code and take appropriate action to resolve the issue