Case IH 19087 – DCU (Dosing Control Unit / Supply Module) or Engine Control Module (ECM): DEF/AdBlue tank temperature is not within acceptable limits.

This code triggers when the temperature sensor inside the Diesel Exhaust Fluid (DEF) tank detects a temperature that is either too high or too low compared to the acceptable operating parameters. This condition is typically caused by a failed temperature sensor, a wiring issue, a stuck-open DEF coolant heater valve, or incorrectly routed coolant lines.

• Tier 4b
• 240 Series Axial-Flow Combines (7240, 8240, 9240)
• Magnum Tractors
• Steiger Tractors
• Puma Tractors (e.g., Puma 200)
• Farmall Tractors (e.g., Farmall 40-50 CVT)
• Case CE Wheel Loaders (e.g., 1121F)
• Compact Track Loaders (e.g., TR340)

1. 1

   Use the CNH Electronic Service Tool (EST) to read the live DEF tank temperature. If the sensor reads an impossible default value (like -40°C or +150°C), the sensor or its wiring has failed.

2. 2

   Inspect the wiring harness and the electrical connector at the top of the DEF tank header unit. Look for corrosion, bent pins, or chafed wires that could cause a short or open circuit.

3. 3

   Verify the heater line with the 'red' band is connected to the correct top tube. Check if the DEF heater control valve is stuck open (incorrect routing or a stuck valve causes hot engine coolant to circulate continuously, physically boiling/overheating the DEF fluid).

4. 4

   Look for accompanying fault codes that might narrow down the issue, such as 19095 (DEF/AdBlue tank temperature sensor plausibility failure) or 19105 (DEF/AdBlue tank heater ECU driver over temperature failure).

1. 1

   Preparation

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

2. 2

   Clean the Area

   Locate the DEF tank and thoroughly clean the area around the top of the DEF header unit (sender unit) to ensure no dirt or debris falls into the tank during removal.

3. 3

   Disconnect Lines

   Carefully disconnect the electrical harness connector from the DEF header unit. Disconnect the DEF suction/return lines and the engine coolant heater lines. Tip: Mark the lines to ensure they are reconnected in the exact same orientation.

4. 4

   Remove the Header Unit

   Remove the mounting bolts or unscrew the locking ring securing the DEF header unit to the tank.

5. 5

   Extraction

   Carefully pull the DEF header unit assembly straight up and out of the tank.

6. 6

   Installation

   Insert the new DEF header unit into the tank, ensuring the new rubber mounting seal/gasket is properly seated to prevent leaks.

7. 7

   Reassembly

   Reinstall the locking ring or mounting bolts. Reconnect the DEF lines, coolant lines, and the electrical connector.

8. 8

   Reset

   Reconnect the battery. Turn the key on and use the CNH EST diagnostic tool to clear fault code 19087. Run the machine and verify that the DEF temperature is now reading within acceptable limits.