Massey Ferguson 003521.16 – ECM or ACM: DEF Quality Sample Problem

The DEF quality sensor has detected an issue with the DEF sample, indicating a potential problem with the quality or condition of the Diesel Exhaust Fluid being used in the Selective Catalytic Reduction (SCR) system. The sensor measures the concentration of urea in the DEF, and this code is triggered when the concentration falls outside the specified range.

• 5710SL
• 5711SL
• 5712SL
• 5713SL T4
• 7714
• 7715
• 7715S
• 7716
• 7716S

1. 1

   Verify DEF quality (poor DEF cause): Perform a visual inspection for cloudiness, discoloration, or particles. Perform a smell test to ensure a slight ammonia scent; petroleum or other odors indicate contamination.

2. 2

   Test DEF concentration (poor DEF cause): Use a DEF refractometer or test strips to verify the urea concentration is within the acceptable range of 32.5% ±0.7%.

3. 3

   Inspect the DEF tank and system (contamination/leak cause): Check for contamination in the tank, leaks in the DEF lines and quick connectors, and signs of crystallization (white crusty deposits) at the injector, exhaust, or connections.

4. 4

   Check electrical connections (wiring cause): Visually inspect the wiring harness and connectors at the DEF quality sensor and dosing module for damage, corrosion, or loose connections. Ensure the sensor has a proper 5V reference and ground.

5. 5

   Review other fault codes: Use a diagnostic tool to check for any other active or inactive SCR system codes that could help pinpoint the issue.

1. 1

   Perform diagnostic checks

   Perform all diagnostic checks listed above to rule out issues with DEF quality, contamination, or wiring.

2. 2

   Drain and refill DEF

   If the DEF is found to be out of specification, drain the DEF tank completely, clean it if necessary, and refill with new, certified DEF.

3. 3

   Clear fault codes

   Clear the fault codes using a diagnostic tool.

4. 4

   Operate the tractor

   Operate the tractor to see if the fault code returns. Some systems may require a specific drive cycle to re-evaluate the DEF quality.

5. 5

   Evaluate sensor replacement

   If the fault code persists after confirming DEF quality and checking the wiring, the DEF quality sensor is likely faulty.

6. 6

   Replace DEF quality sensor

   Disconnect the vehicle's batteries. Remove the DEF tank or a protective cover to access the sensor. Disconnect the electrical and coolant line connections from the sensor head unit (cap or plug lines to prevent spillage). Unscrew the retaining ring, remove the old sensor, and install the new sensor with a new gasket. Reconnect all lines, reinstall the tank and covers, and reconnect the batteries.

7. 7

   Perform system reset

   After replacement, perform a system reset or relearn procedure using a diagnostic tool to ensure the ECM recognizes the new sensor.