Case IH 17699 (F-519051-09) - ECU – Engine Control Unit (ECU): CAN timeout error from DEF/Adblue tank level sensor - AT1T1I Message

The Engine Control Unit (ECU) has lost communication with the DEF (Diesel Exhaust Fluid) tank level sensor over the CAN (Controller Area Network) bus. Specifically, the ECU is not receiving the "AT1T1I" data message, which broadcasts the DEF tank level and temperature data from the sensor. Because the ECU cannot verify the amount or temperature of the emissions fluid, it will log this code and eventually trigger an engine derate (reduced power) to comply with emissions regulations.

• VESTRUM CVX
• Magnum
• Steiger
• Puma
• Maxxum
• Farmall
• Axial-Flow 7130
• Axial-Flow 7230
• Axial-Flow 8240
• Axial-Flow 9240
• Patriot
• Titan

1. 1

   Inspect the wiring harness and the electrical connector at the DEF tank header for physical damage, corrosion, or loose pins.

2. 2

   Verify that the DEF tank level sensor is receiving proper voltage and has a solid ground connection.

3. 3

   Check the CAN High and CAN Low lines between the DEF header and the ECU for continuity, high resistance, or shorts to ground/power.

4. 4

   Open the DEF tank and check for fluid contamination (such as diesel fuel), which can cause chemical reactions that destroy the sensor internally.

5. 5

   Look for other CAN bus fault codes. If multiple sensors are dropping offline, the issue is likely a main CAN bus wiring fault rather than the DEF sensor itself.

1. 1

   Power down ECU

   Turn off the machine, remove the key, and disconnect the battery to power down the ECU.

2. 2

   Clean DEF tank area

   Clean the area around the top of the DEF tank to prevent dirt from falling into the tank during removal.

3. 3

   Disconnect electrical connector

   Disconnect the electrical connector from the DEF header.

4. 4

   Disconnect fluid and coolant lines

   Carefully disconnect the DEF fluid supply and return lines, as well as the engine coolant lines (if equipped with a heated DEF header). Note: Be prepared to catch minor fluid spills.

5. 5

   Remove mounting hardware

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

6. 6

   Extract old DEF header

   Carefully extract the old DEF header assembly from the tank.

7. 7

   Insert new DEF header

   Insert the new DEF header assembly, ensuring the new O-ring/seal is properly seated to prevent leaks and contamination.

8. 8

   Secure mounting hardware

   Secure the mounting bolts/locking ring.

9. 9

   Reconnect lines and connector

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

10. 10

    Reconnect battery

    Reconnect the battery and turn the key to the ON position.

11. 11

    Clear fault codes

    Use a diagnostic scanner (such as the Case IH Electronic Service Tool - EST) to clear the fault codes.

12. 12

    Verify repair

    Start the engine and verify that the DEF level is reading correctly on the cab display and that the fault code does not return.