Massey Ferguson U 1761 (2) – ECU: Urea Tank Level Sensor error: Range error of tank level

The control module expects to receive a continuous or periodic signal regarding the fluid level in the DEF (Diesel Exhaust Fluid) tank, but the signal has been lost, interrupted, or not received within the programmed time threshold. This is typically caused by a severed wire, a heavily corroded connector, a failed sensor, or a CAN bus communication failure if the sensor operates on a sub-network.

• 8600 Series
• 8650
• 8660
• 8670
• 8680
• 8690
• 7600 Series
• 4700 Series
• 4707
• 4708
• 4709
• 4710

1. 1

   Verify the actual physical level of the DEF in the tank to ensure it isn't completely empty or overfilled.

2. 2

   Inspect the DEF fluid for contamination (e.g., diesel fuel, water, or dirt). The chemistry of DEF is unforgiving; tiny amounts of dirt or diesel can ruin the sensor and trigger range errors.

3. 3

   Inspect the wiring harness leading to the DEF tank header module. Look for chafing, pinched wires, or melted insulation. Disconnect the sensor and check the pins for corrosion or moisture.

4. 4

   Use a diagnostic tool (such as AGCO EDT or Jaltest) to read the live data from the DEF level sensor. If the voltage or percentage jumps erratically or is frozen at an impossible value while fluid is present, the sensor has failed internally.

1. 1

   Preparation

   Turn off the tractor, remove the key, and disconnect the battery to prevent electrical shorts.

2. 2

   Clean the Area

   Thoroughly clean the top of the DEF tank and the area around the sensor mounting flange. Treat the tank neck like a jet fuel filler—absolutely no dirt can be allowed to fall into the tank during this process.

3. 3

   Disconnect Lines

   Carefully disconnect the heated DEF supply and return lines from the top of the sensor module. Be extremely careful not to kink the lines or nick the sealing O-rings, as this will cause air ingress and priming faults later.

4. 4

   Disconnect Electricals

   Unplug the electrical connector from the sensor.

5. 5

   Remove the Sensor

   Unscrew the retaining ring or mounting bolts holding the sensor module to the tank. Carefully pull the old sensor assembly straight up and out of the tank.

6. 6

   Install the New Sensor

   Insert the new AGCO DEF sensor assembly. Ensure the new rubber O-ring/gasket is properly seated to prevent dirt and moisture from entering the tank. Secure the retaining ring/bolts.

7. 7

   Reconnect

   Reconnect the heated DEF lines and the electrical harness.

8. 8

   Refill and Reset

   Refill the tank with fresh, high-quality DEF. Reconnect the battery. Connect your diagnostic tool to clear the U 1761 (2) fault code and reset the SCR system out of derate mode.