Case IH 19144 – Engine Control Unit (ECU): CAN timeout error from DEF/AdBlue quality sensor

The control module has lost communication with the DEF (Diesel Exhaust Fluid) quality sensor over the CAN (Controller Area Network) bus. The sensor is failing to send its data packets (which include DEF concentration, temperature, and level) to the network within the expected timeframe, triggering an SCR alarm, an engine derate (inducement), and a warning light.

• Tier 4b
• 240 Series Axial-Flow Combines (7240, 8240, 9240)
• Magnum tractors
• Steiger tractors
• SV340B
• TR340

1. 1

   Visually inspect the DEF quality sensor wiring harness and connector for chafed wires, corrosion, moisture intrusion, or pushed-out pins.

2. 2

   Verify that the sensor is receiving proper operating voltage and has a solid ground at the connector.

3. 3

   Check the CAN High and CAN Low communication lines for continuity and proper resistance (typically 60 ohms across the network) between the DEF sensor connector and the ECU.

4. 4

   Inspect the DEF fluid to ensure it is not severely degraded, frozen, or crystallized, as harsh environments and chemical reactions from contaminated fluid can cause internal failure of the sending unit.

1. 1

   Prep the Machine

   Turn off the equipment, remove the key, and disconnect the battery to prevent electrical shorts.

2. 2

   Access the Sensor

   Locate the DEF header assembly on top of the DEF tank. Clean the area around the sensor to prevent dirt from falling into the tank.

3. 3

   Disconnect

   Unplug the electrical connector from the DEF quality sensor. Disconnect any DEF fluid lines attached to the header unit (be prepared to catch minor spills).

4. 4

   Remove the Sensor

   Remove the mounting screws or locking ring securing the DEF header to the tank. Carefully pull the entire DEF sensor/header assembly straight up and out of the tank.

5. 5

   Install the New Part

   Insert the new DEF quality sensor assembly into the tank, ensuring the gasket/O-ring is properly seated. Secure the mounting hardware.

6. 6

   Reconnect

   Reattach the DEF fluid lines and plug in the electrical connector. Reconnect the battery.

7. 7

   Reset the ECU

   Connect the Case IH Electronic Service Tool (EST) to clear the fault code and perform an 'Engine Restart Counter Reset / Unlock' to return the machine to normal operation.