Case IH 19140 – Engine Control Module (ECM) / SCR Control System: DEF/AdBlue concentration is out of range

The DEF Quality Sensor has detected that the urea concentration in the DEF tank is outside the acceptable specification (32.5%), or the sensor itself is providing an erratic/invalid reading. This triggers an SCR failure warning and will eventually lead to an engine power loss/derate.

• Tier 4b
• 240 Series Axial-Flow Combines
• Steiger Tractors
• Quadtrac Tractors
• Quadtrac 500
• Magnum Tractors
• Puma Tractors
• Maxxum Tractors

1. 1

   Test the DEF fluid using a refractometer to ensure it reads exactly 32.5% urea concentration

2. 2

   Check for visual signs of water dilution, dirt, or diesel fuel in the DEF tank (diesel fuel usually triggers code 19141 alongside 19140)

3. 3

   Inspect the DEF Quality Sensor wiring harness and connector on top of the DEF tank for corrosion, moisture, or loose connections caused by venting ammonia gas

4. 4

   Check for related sensor codes like 19142 (temperature failure) or 19144 (CAN timeout) which indicate an electrical failure of the sensor/header unit

1. 1

   Drain contaminated DEF fluid

   If the DEF fluid tests bad (diluted/contaminated): Place a drain pan under the DEF tank and completely drain the contaminated fluid.

2. 2

   Flush the DEF tank

   Flush the tank with distilled water or fresh, known-good DEF.

3. 3

   Replace the DEF filter

   Replace the DEF filter, as contaminated fluid often compromises the filter media.

4. 4

   Refill the DEF tank

   Refill the tank with fresh, high-quality DEF (32.5%).

5. 5

   Clear fault codes

   Use an Electronic Service Tool (EST) or the AFS Pro display to clear the fault codes.

6. 6

   Disconnect battery

   If the DEF fluid tests good (Sensor Failure): Turn off the machine and disconnect the battery to prevent electrical shorts. (Note: Check with a Case IH dealer to see if an ECM software update is available to bypass the tank sensor requirement before replacing the sensor).

7. 7

   Locate DEF Header Unit

   Locate the DEF Header Unit on top of the DEF tank.

8. 8

   Disconnect lines and connector

   Disconnect the electrical connector and the DEF supply/return lines from the header.

9. 9

   Remove faulty assembly

   Unbolt and remove the faulty DEF Header/Quality Sensor assembly from the tank.

10. 10

    Install new DEF Header Unit

    Install the new DEF Header Unit and secure the mounting bolts.

11. 11

    Reconnect lines and harness

    Reconnect the DEF lines and the electrical harness.

12. 12

    Reconnect battery and clear codes

    Reconnect the battery, turn the key on, and clear the fault codes using your diagnostic tool.