Case IH 19024 (DTC 92EE) - ECU – Engine Control Unit (ECU): CAN timeout error from NH3 sensor - NH3Sens message

This code indicates a communication failure on the Controller Area Network (CAN) bus. The Engine Control Unit (ECU) is expecting to receive the "NH3Sens" data message from the Ammonia (NH3) sensor's processor, but the message has timed out. The NH3 sensor is a critical part of the Selective Catalytic Reduction (SCR) emissions system, used to monitor the elimination of residual ammonia downstream of the Clean Up Catalyst (CUC).

• MAXXUM T4E
• 240 Series Axial-Flow Combines
• Farmall 110A
• Farmall 120A
• Farmall 130A
• Farmall 140A
• Farmall 110U
• Maxxum 115
• WD2505 High Speed Windrower
• Case 580N Backhoe Loaders
• 821F Wheel Loaders
• 921F Wheel Loaders

1. 1

   Check Power and Ground: Verify that the NH3 sensor processor module is receiving proper battery voltage and has a solid ground.

2. 2

   Inspect the CAN Bus Wiring: Inspect the wiring harness between the NH3 sensor processor and the Engine ECU. Look for chafed wires, corrosion in the connector pins, or loose connections that could interrupt CAN communication.

3. 3

   Check for Accompanying Codes: Look for other CAN bus errors (e.g., DTC 931B / 19225 CAN C Bus off passive failure). If multiple modules are timing out, the entire CAN network may be compromised by a short circuit or a different faulty module.

1. 1

   Prepare machine

   Turn off the machine, ensure the exhaust system has completely cooled, and disconnect the battery.

2. 2

   Locate sensor

   Locate the NH3 sensor. It is mounted in the exhaust stream downstream of the Clean Up Catalyst (CUC) / SCR muffler.

3. 3

   Remove heat shield (if applicable)

   Depending on the machine model (e.g., Farmall tractors), you may need to remove the SCR muffler and catalyst upper heat shield to gain access to the sensor.

4. 4

   Disconnect electrical connector

   Disconnect the electrical connector from the NH3 sensor processor module.

5. 5

   Remove NH3 sensor

   Carefully unscrew and remove the Ammonia (NH3) sensor from the exhaust pipe.

6. 6

   Install new NH3 sensor

   Install the new NH3 sensor into the exhaust pipe and tighten to OEM specifications.

7. 7

   Reconnect electrical harness

   Reconnect the electrical harness to the new sensor's processor.

8. 8

   Reinstall components

   Reinstall any heat shields or clamps that were removed during disassembly.

9. 9

   Test and verify

   Reconnect the battery, use a diagnostic service tool to clear the fault codes, and run the engine to operating temperature to verify the CAN timeout code does not return.