Case IH 19790 – Engine Control Unit (ECU) or Dosing Control Unit (DCU) / SCR system controller: Level 1 warning is active due to Low DEF/AdBlue Level

This code indicates that the Diesel Exhaust Fluid (DEF) in the tank has dropped below the first warning threshold. When this code is active, the machine's emissions system will typically trigger a Level 1 inducement, which results in an engine torque reduction to encourage the operator to refill the tank.

• Tier 4b
• Farmall
• Farmall 90C
• Farmall 110U
• Maxxum
• Puma
• Magnum
• Steiger
• Axial-Flow
• Axial-Flow 7230
• Axial-Flow 8230
• N-Series Loaders
• Wheel Loaders
• 1121F
• Compact Track Loaders

1. 1

   Visually verify the actual fluid level in the DEF tank (do not rely solely on the cab monitor)

2. 2

   Inspect the DEF fluid for contamination, dirt, or crystallization, which can cause the sensor float to stick or damage the ultrasonic sensor

3. 3

   Inspect the wiring harness and the electrical connector at the DEF head unit for damage, corrosion, or loose pins

4. 4

   Ensure the Coolant Control Valve (CCV) is not stuck open, which can boil the DEF fluid and damage the sensor assembly

5. 5

   Check with a dealer to see if there is a software update available for the ECU/DCU to adjust DEF level sensor logic

6. 6

   Use the Case IH Electronic Service Tool (EST) to monitor the live DEF level sensor voltage/reading and verify if the sensor is completely dead or just stuck

1. 1

   Refill the Tank

   Fill the DEF tank with fresh, high-quality DEF (ISO 22241 standard). Turn the key on and wait to see if the system registers the new level and clears the code.

2. 2

   Clear Codes

   If the tank is full but the code persists, connect the Case IH EST laptop to clear the code or perform a manual SCR system reset.

3. 3

   Drain the Tank

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

4. 4

   Disconnect Lines

   Disconnect the electrical connector, the DEF supply and return lines, and the engine coolant heating lines from the top of the DEF head unit.

5. 5

   Remove the Sensor

   Remove the locking ring or mounting bolts securing the DEF head unit to the tank and carefully extract the old unit.

6. 6

   Install the New Unit

   Install the new DEF head unit assembly, ensuring the new O-ring/seal is properly seated to prevent leaks.

7. 7

   Reassembly

   Reconnect the coolant lines, DEF lines, and the electrical connector.

8. 8

   Refill and Test

   Refill the tank with DEF, turn the key to the ON position to allow the new sensor to initialize, and use the EST to clear any remaining fault codes.