Case IH 19045 (DTC 94BE) - ECU – Engine Control Unit (ECU): Timeout error of message from ECU to NOx downstream sensor

The Engine Control Unit (ECU) transmits a specific CAN bus message (EDC2NOx) to the downstream NOx sensor containing critical information about the exhaust dew point status. The fault is logged when the ECU detects that this CAN message has timed out, meaning communication between the ECU's CAN controller and the NOx sensor's internal module has been lost or interrupted.

• MAXXUM T4E
• Farmall (110A-140A)
• Puma (150-220)
• Optum (270-300)
• Magnum
• Steiger

1. 1

   Verify the presence and correct connection of the EDC/ECU to the CAN network

2. 2

   Inspect the CAN wiring harness between the ECU and the downstream NOx sensor for disconnected cables, broken wires, or chafing

3. 3

   Test the CAN High and CAN Low lines for continuity and check for short circuits to ground or battery voltage

4. 4

   Check for other CAN-related fault codes to verify the correct functioning of the ECU's CAN controller

1. 1

   Power Down

   Turn off the machine, remove the key, and disconnect the battery to prevent electrical spikes.

2. 2

   Locate Components

   Locate the downstream NOx sensor (mounted on the exhaust tailpipe, directly after the SCR catalyst) and the Engine ECU.

3. 3

   Inspect Connectors

   Disconnect the 5-pin harness at the NOx sensor module and the corresponding connector at the ECU. Inspect the pins for corrosion, pushed-back terminals, or moisture ingress. Clean and apply dielectric grease if minor corrosion is found.

4. 4

   Perform Continuity & Short Tests

   Using a multimeter, measure the resistance of the CAN lines between the ECU and the NOx sensor connector. Resistance should be continuous (close to 0 ohms). Next, check for continuity between the CAN lines and chassis ground to rule out a short circuit.

5. 5

   Check Sensor Power/Ground

   Turn the key to the ON position (engine off) and verify that the NOx sensor connector is receiving proper 12V power and ground.

6. 6

   Replace Sensor (If Wiring is Good)

   If the wiring harness, power, and ground are all intact, the CAN transceiver inside the NOx sensor module has likely failed. Replace the downstream NOx sensor.

7. 7

   Clear Codes & Warm Up

   After replacement, clear the fault codes. Turn the key switch ON. The dew point (warm-up cycle) will begin. The sensor will read 'not ready' until exhaust moisture is wicked off the tip, after which it will read 'Ready' and resume normal CAN communication.