Case IH 19171 – Engine Control Unit (ECU) or Dosing Control Unit (DCU): DEF/AdBlue Conductivity Error (Urea Conductivity Error)

The DEF quality sensor has detected that the electrical conductivity of the fluid in the DEF tank is out of the acceptable range, indicating the fluid is degraded, diluted, or contaminated.

• Tier 4b
• Magnum
• Puma
• Optum
• Maxxum
• Patriot Sprayers
• Axial-Flow Combines
• Case CE wheel loaders
• Case CE excavators

1. 1

   Test the DEF Quality: Use a DEF refractometer to test the fluid currently in the tank. It must read exactly 32.5% urea. If it does not, the fluid is the problem.

2. 2

   Inspect for Contamination: Check the tank for signs of water dilution, diesel fuel cross-contamination, or heavy dirt/debris.

3. 3

   Inspect the Wiring Harness: Check the electrical connector at the top of the DEF tank header. Look for pushed-out pins, corrosion, or chafing on the wiring harness leading back to the ECU/DCU.

4. 4

   Check for Software Updates: Verify with an Electronic Service Tool (EST) that the ECU is on the latest software revision to address overly sensitive DEF quality sensor parameters.

1. 1

   Drain DEF tank

   Scenario A (Fluid is Contaminated/Degraded): Place a suitable drain pan under the DEF tank and completely drain the degraded fluid.

2. 2

   Flush tank

   Flush the tank with distilled water or fresh DEF to remove crystallized urea or debris.

3. 3

   Replace filter

   Replace the DEF tank header suction screen/filter.

4. 4

   Refill tank

   Refill the tank with fresh, high-quality, API-certified DEF.

5. 5

   Clear codes

   Cycle the key and use the EST to clear the fault codes.

6. 6

   Disconnect battery

   Scenario B (Sensor Failure - Fluid is verified good at 32.5%): Disconnect the machine's battery.

7. 7

   Clean tank top

   Thoroughly clean the top of the DEF tank around the header to prevent dirt from falling into the tank during removal.

8. 8

   Disconnect harness

   Disconnect the electrical harness connector from the header.

9. 9

   Disconnect lines

   Disconnect the DEF supply line, DEF return line, and the engine coolant lines (which run through the header to thaw frozen DEF). Note: Clamp the coolant lines to prevent coolant loss.

10. 10

    Remove mounting hardware

    Remove the mounting ring or retaining bolts securing the header to the tank.

11. 11

    Remove header

    Carefully pull the old DEF tank header assembly out of the tank.

12. 12

    Insert new header

    Insert the new DEF tank header assembly, ensuring the new rubber gasket/O-ring is properly seated.

13. 13

    Reinstall hardware

    Reinstall the retaining ring/bolts.

14. 14

    Reconnect lines and harness

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

15. 15

    Clear codes

    Reconnect the battery, turn the key on, and clear the fault codes using the EST.