Case IH 3595 – Engine Control Module (ECM / EDC) or Dosing Control Unit (DCU): Minimum urea level 1

The Diesel Exhaust Fluid (DEF / Urea) in the tank has dropped below the first minimum warning threshold. If the tank is physically full, it indicates a malfunction in the DEF tank level sensor (DEF Head Unit) or its associated wiring circuit.

• Magnum
• Puma
• Steiger
• Maxxum
• Optum
• Farmall
• Combines
• Case Construction equipment
• compact track loaders

1. 1

   Verify physical fluid level: Visually inspect the DEF tank to confirm if it is actually low. If empty or low, the code is operating as designed.

2. 2

   Inspect DEF quality: Check for contaminated or poor-quality DEF, which can cause chemical reactions that damage the sending unit sensor.

3. 3

   Check wiring and connections: Inspect the wiring harness leading to the DEF tank header unit for chafed wires, corrosion in the connector pins, or moisture intrusion.

4. 4

   Test the sensor: If the tank is full and wiring is intact, use a multimeter or the CNH Electronic Service Tool (EST) to monitor the DEF level sensor's voltage/resistance output to the ECM. If it reads empty while submerged, the unit has failed.

1. 1

   Refill the Tank

   Fill the tank with high-quality, automotive-grade Diesel Exhaust Fluid (32.5% urea / 67.5% deionized water). Cycle the ignition key to see if the code clears.

2. 2

   Drain the Tank

   If the sensor is faulty, place a clean drain pan under the DEF tank and drain the fluid.

3. 3

   Disconnect the Header Unit

   Disconnect the electrical connector and the DEF fluid supply/return lines from the top of the DEF tank header unit.

4. 4

   Remove the Faulty Sensor

   Unscrew the locking ring or mounting bolts securing the DEF level sensor assembly to the tank and carefully pull the unit out.

5. 5

   Install the New Sensor

   Insert the new DEF head unit/level sensor into the tank, ensuring the sealing O-ring is properly seated to prevent leaks. Tighten the locking ring/bolts.

6. 6

   Reconnect and Refill

   Reconnect the fluid lines and electrical harness. Refill the tank with clean DEF.

7. 7

   Clear Codes

   Turn the key to the ON position. Verify that the dashboard DEF gauge now registers the correct fluid level. Use a diagnostic tool to clear the stored 3595 fault code from the ECM/DCU.