ECU 005435.09 – CAN Bus Message Cannot Be Received, Information from DEF Dosing Unit. John Deere System Advisory.

ECU 005435.09 (ECU 5435.09)

Code: 005435.09

Shortcode: 5435.09


This diagnostic trouble code indicates a data transfer problem between the Engine Control Unit (ECU) and the DEF dosing unit. The ECU is unable to receive CAN bus messages from the DEF dosing unit, which can impact the DEF dosing system’s performance.


The ECU may limit or adjust the operation of the DEF dosing system to ensure safe operation and emissions compliance. This could result in reduced engine power and performance.


  • Inspect CAN Bus Wiring and Connections: Check for damaged, frayed, or loose wiring and connectors associated with the CAN bus between the ECU and the DEF dosing unit. Repair or replace as necessary.
  • Test CAN Bus Communication: Use diagnostic tools to test the CAN bus communication between the ECU and the DEF dosing unit. Ensure that there are no interruptions or data transfer issues.
  • Check for Loose Connections: Verify that all connections between the ECU and the DEF dosing unit are secure and free of corrosion.
  • Verify DEF Dosing Unit Function: Ensure that the DEF dosing unit is functioning correctly and is able to send CAN bus messages.
  • Reset ECU and Monitor System: After resolving the issue, reset the ECU to clear the fault code and monitor the system to ensure normal operation.


Maintaining proper communication between the ECU and the DEF dosing unit is crucial for accurate DEF dosing and emissions control. Regular inspections and timely maintenance can help prevent communication-related issues.

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