Massey Ferguson 3515.11 – Engine Control Unit (ECU): DEF Tank Temp Sensor Error (ECU)

This code indicates a general error or malfunction with the Diesel Exhaust Fluid (DEF) Tank Temperature Sensor. A failure means the engine control module is receiving erratic, missing, or out-of-range temperature data from the DEF tank.

• 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

   Visual & Wiring Inspection: Disconnect the DEF tank sensor wiring harness. Inspect the connectors for damaged wires, bent pins, corrosion, or water ingress. Repair any damaged wiring.

2. 2

   Fluid Level & State: Ensure the DEF tank is adequately filled and verify that the DEF is not frozen solid (if operating in extreme cold, allow the built-in heaters time to thaw the fluid while idling).

3. 3

   Fluid Quality Check: Use a DEF refractometer to verify the DEF quality is at an acceptable value (32.5% urea concentration). Contaminated DEF can cause sensor scaling and erratic readings.

4. 4

   System Reset Test: Clear the fault codes using a diagnostic tool. Start the engine and run it on high idle (1000 RPM or higher) for 2 minutes. Turn the engine off and leave the key off for 15 seconds. Restart and run on high idle for another 2 minutes. If the code returns as active, the sensor/header assembly has failed internally and requires replacement.

1. 1

   Preparation

   Turn off the machine and disconnect the battery.

2. 2

   Drain the Tank

   Drain the DEF tank completely to prevent spills and contamination.

3. 3

   Disconnect Lines

   Carefully disconnect the electrical connector and the DEF fluid lines from the top of the DEF header assembly.

4. 4

   Remove the Sensor Assembly

   Unbolt or unscrew the retaining ring holding the DEF header/sensor unit in the tank and carefully pull the float/sensor unit assembly out.

5. 5

   Install New Part

   Insert the new DEF header/temperature sensor assembly into the tank, ensuring the gasket/O-ring is properly seated to prevent leaks. Secure the retaining ring.

6. 6

   Reconnect & Refill

   Reconnect the DEF lines and the electrical harness. Refill the tank with fresh, ISO 22241 certified Diesel Exhaust Fluid.

7. 7

   Software Reset

   Reconnect the battery. Connect an OEM or compatible diagnostic scan tool to the diagnostic port. Clear all active and inactive fault codes. Depending on the exact model, you may need to run a "DEF System Test" or "Aftertreatment Relearn Procedure" so the ECM recognizes the new sensor.