Case IH 19168 (DTC 1B4E) - ECU – Engine Control Module (ECM) or Dosing Control Unit (DCU): DEF/AdBlue quality sensor internal failure (Temperature sensor value is lower than expected)

The fault indicates an internal failure within the DEF (Diesel Exhaust Fluid) quality sensor assembly, specifically that the integrated temperature sensor is reporting a minimum signal range or a value lower than the expected threshold.

• MAXXUM T4E
• Case IH 240 Series Axial-Flow Combines (7230, 8230, 9230)
• Case IH Magnum Tractors
• Case IH / New Holland T7 Series (Tier 4B) Tractors
• Case IH Farmall models
• Case IH Maxxum models

1. 1

   Check DEF fluid quality for contamination or poor quality that can interfere with sensor readings or damage the sending unit

2. 2

   Inspect wiring harness and connectors leading to the DEF header unit for corrosion, moisture, or physical damage

3. 3

   Check the DEF tank vent hose to ensure it is not plugged with dirt or debris, which can cause pressure issues

4. 4

   Check for overlapping codes (such as level sensor faults or dosing valve short circuits) that might indicate a broader wiring issue or a completely failed DEF head unit

5. 5

   Drain a sample of the DEF to check for crystallization or debris that might be coating the sensor

1. 1

   Preparation

   Turn off the machine and ensure the exhaust and DEF systems have cooled down.

2. 2

   Drain the Tank

   Drain the DEF tank completely to prevent spills and remove any potentially contaminated fluid.

3. 3

   Disconnect the Unit

   Locate the DEF Head Unit on the DEF tank. Carefully disconnect the electrical harness connectors and the DEF fluid lines.

4. 4

   Remove the Sensor Assembly

   Remove the mounting flange screws or locking ring securing the DEF header to the tank. Carefully pull the old sending unit out of the tank.

5. 5

   Clean the Area

   Clean the mounting surface on the tank to ensure a proper seal for the new unit.

6. 6

   Install the New Unit

   Insert the new DEF Head Unit into the tank and secure the mounting flange.

7. 7

   Reconnect

   Reattach the DEF fluid lines and plug in the electrical connectors.

8. 8

   Refill and Clear Codes

   Refill the tank with fresh, high-quality DEF. Use a dealer laptop or diagnostic tool to clear the fault codes and reset the SCR system.