ECU 003516.01 – Aftertreatment DEF Concentration Extremely Low. John Deere System Advisory.

ECU 003516.01 (ECU 3516.01)

Code: 003516.01

Shortcode: 3516.01


This fault code is set when the Diesel Exhaust Fluid (DEF) concentration in the tank is detected to be extremely low, potentially indicating issues with DEF quality or contamination that could impair the aftertreatment system’s effectiveness in reducing emissions.


The ECU might restrict engine performance or increase the frequency of DEF dosing to compensate for the low concentration, aiming to meet emission standards.


  • Inspect DEF Quality: Check the DEF for contamination or dilution that may reduce its concentration below the acceptable range.
  • Refill or Replace DEF: If the DEF is found to be of poor quality, drain the tank and refill it with a high-quality DEF.
  • Test DEF Sensor and System: Ensure that the DEF concentration sensor and related systems are functioning properly to accurately detect DEF quality.
  • Reset ECU and Perform Emission Tests: After addressing the DEF issues, reset the ECU to clear the fault code and conduct emission tests to ensure the aftertreatment system operates efficiently.


Maintaining proper DEF quality is crucial for effective NOx reduction in modern diesel engines. Regular checks of DEF levels and quality can prevent issues related to emission control system performance.

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