Case IH 17780 (F-3031-11) - ECU – Engine Control Unit (ECU) / Engine Electronic Management (EEM) or Dosing Control Unit (DCU): DEF/AdBlue tank temperature sensor signal error via CAN message

The monitoring system has detected that the DEF tank temperature sensor value is implausible, erratic, or missing. Because the temperature sensor is integrated into the DEF header unit, this code typically points to a failure of the sensor itself, a wiring defect, or a communication issue on the CAN bus. Engine power will be reduced (derated) after a certain time if not corrected.

• VESTRUM CVX
• Magnum Series Tractors (250, 280, 310, 340, 380)
• Steiger Series Tractors (370, 420, 470, 500, 540, 580, 620)
• Axial-Flow Combines (5130, 6130, 7130, 7240, 8240, 9240)
• Puma Series Tractors
• Maxxum Series Tractors
• Optum Series Tractors
• Patriot / Trident Sprayers

1. 1

   Stop the engine and let it cool before starting work. Do not start the engine during the service procedures.

2. 2

   Inspect the DEF tank temperature sensor wiring harness for loose contacts, defective wires, or rodent damage.

3. 3

   Inspect the connector terminals at the DEF header for debris or water ingress, which can often happen as a consequence of pressure washing.

4. 4

   Inspect for any damaged or loose machine earths (grounds) and connector pins.

5. 5

   Save the error log and then erase it to see if the CAN message fault is an active, recurring issue or a stored anomaly.

1. 1

   Prepare machine for service

   Turn off the machine, disconnect the battery, and ensure the engine and exhaust systems are cool.

2. 2

   Clean work area

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

3. 3

   Disconnect electrical connector

   Disconnect the main electrical harness connector from the DEF header unit.

4. 4

   Disconnect fluid lines

   Carefully disconnect the DEF supply and return lines from the header.

5. 5

   Remove mounting hardware

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

6. 6

   Remove old DEF header

   Pull the old DEF header unit (containing the temperature, level, and quality sensors) straight up and out of the tank.

7. 7

   Install new DEF header

   Install the new DEF header unit, ensuring the sealing ring/O-ring is properly seated to prevent leaks.

8. 8

   Reinstall hardware and connections

   Reinstall the mounting ring/bolts, reconnect the fluid lines, and plug in the electrical connector.

9. 9

   Clear codes and verify

   Reconnect the battery, turn on the machine, and use a diagnostic tool to clear the fault codes and verify that the ECU is now receiving a plausible temperature reading.