ECU 003517.12 – DEF Tank Fluid Level Error. John Deere System Advisory.

ECU 003517.12 (ECU 3517.12)

Code: 003517.12

Shortcode: 3517.12


This fault code is triggered when the DEF tank fluid level sensor detects an issue with accurately measuring the fluid level. This can lead to incorrect DEF dosing and impact the effectiveness of the aftertreatment system.


The ECU may issue warnings or limit certain functions to prevent potential damage due to incorrect DEF levels. This can result in reduced performance and possible non-compliance with emissions standards.


  • Inspect DEF Level Sensor: Check the sensor for any physical damage or signs of wear that could affect its accuracy.
  • Test Sensor Functionality: Use diagnostic tools to verify that the sensor is providing accurate readings. Replace the sensor if it is malfunctioning.
  • Check Electrical Connections: Ensure all wiring and connectors related to the sensor are secure and free of corrosion or damage.
  • Reset ECU and Monitor: After addressing the issue, reset the ECU to clear the fault code and monitor the DEF levels to ensure accurate reporting.


Accurate DEF fluid level measurement is essential for proper DEF dosing and the effective operation of the emission control system. Regular maintenance and checks can help prevent sensor errors and ensure system reliability.

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