Massey Ferguson 3519.03 – Engine ECU: DEF Tank Temperature Sensor Issue (ECU)

The Electronic Engine Management (EEM) system has detected that the temperature value coming from the Diesel Exhaust Fluid (DEF) tank sensor is implausible, likely due to a broken wire, disconnected plug, or an internally failed sensor (Signal High Error or Open Circuit).

• 4710
• 7724S
• 5712SL
• 7722S
• 7722
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 4708
• 7726S
• 4707
• 4709
• 5711SL
• 7718S
• 7719
• 7714
• 7716S
• T4 (2015-2021)
• 7720
• Tier 4 (2015-2021)
• 7715S
• 7724
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7626

1. 1

   Check the error log in the diagnostic tool and erase it to see if the fault is active or stored

2. 2

   Inspect the wiring harness connecting the DEF tank header to the ECU for loose contacts, chafed wires, or an open circuit

3. 3

   Visually inspect the DEF tank header for mechanical stress due to vibration, freezing conditions, or heavy crystallization of DEF fluid on the sensor probe

4. 4

   Ensure the DEF tank cap is sealed and the breather is clear to rule out contaminated DEF causing cascading sensor failures

1. 1

   Power Down

   Turn off the machine and disconnect the battery to ensure safety while working on the ECU wiring.

2. 2

   Test the Harness

   Use a multimeter to test the continuity of the DEF temperature sensor circuit from the tank header connector to the ECU pins.

3. 3

   Repair Wiring

   If a break or short is found in the harness, repair the wiring and re-test.

4. 4

   Replace the Sensor Header

   If the wiring is intact, the sensor itself has failed. The temperature sensor is integrated into the DEF tank header assembly (which also houses the level and quality sensors).

5. 5

   Drain and Swap

   Drain the DEF tank. Remove the mounting bolts for the DEF header assembly and pull the unit out. Install the new DEF header assembly.

6. 6

   Refill and Clear Codes

   Refill the tank with fresh, clean DEF. Reconnect the battery, turn on the machine, and use a diagnostic tool to clear the 003519.03 code and run a system test.