Massey Ferguson 3031.04 – Engine Control Unit (ECU): Issue With The Temperature Of The DEF Tank Temperature Sensor

The Engine Control Unit has detected that the voltage signal from the Diesel Exhaust Fluid (DEF) tank temperature sensor is below normal or shorted to a low source (short to ground). This prevents the system from accurately measuring the DEF fluid temperature, which is critical for proper DEF dosing and emission control.

• 4710
• 7724S
• 5712SL
• Interim Tier 4 (2012-2015)
• 7722
• 7722S
• 7615
• 5613
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 7616
• 7618
• 5608
• 4708
• 7619
• 7626
• 7726S
• 7624
• 4707
• 4709
• 5711SL
• 7614
• 7718S
• 5610
• 7620
• 7719
• 7714
• 7716S
• T4 (2015-2021)
• 5612
• 7622
• 7720
• Tier 4 (2015-2021)
• 5611
• 7715S
• 5609
• 7724
• 4608
• 4609
• 4610
• 5710
• 5711
• 6612
• 6613
• 6614
• 6615
• 6616
• 6712
• 6713
• 8650
• 8660
• 8670
• 8680
• 8690
• 9540
• 9560

1. 1

   Inspect the DEF tank temperature sensor, the wiring harness, and the connectors for signs of physical damage, corrosion, or loose contacts.

2. 2

   Measure the voltage at the temperature sensor using a multimeter to confirm if it matches the expected OEM specifications. A low voltage reading confirms a short to ground.

3. 3

   Check the wiring harness between the DEF tank temperature sensor and the ECU to isolate whether the short to ground is in the wiring or internal to the sensor itself.

1. 1

   Isolate the Fault

   Disconnect the DEF tank temperature sensor. If the short-to-ground fault changes to an open-circuit fault on your diagnostic tool, the sensor is internally shorted and must be replaced. If the short-to-ground fault remains, the wiring harness is pinched or chafed against the chassis and must be repaired.

2. 2

   Repair/Replace

   Repair the damaged section of the wiring harness, or replace the defective DEF tank temperature sensor/sender unit. Ensure the tank neck and surrounding area are spotless before removing the sensor to prevent dirt from contaminating the DEF fluid.

3. 3

   Reassemble

   Install the new sensor, ensuring O-rings are seated properly to prevent air ingress or leaks. Reconnect the wiring harness.

4. 4

   Clear and Calibrate

   Connect a diagnostic tool (such as WinEEM or equivalent) to clear the fault codes from the ECU. Reset the ECU and allow the system to recalibrate to ensure it recognizes the new sensor and reads the temperature accurately.