Case IH 19044 – Engine Control Module (ECM) or Aftertreatment Control Module (ACM): Timeout of ECM to NOx sensor downstream Dew Point Message

CAN bus communication failure between the Engine Control Module (ECM) and the downstream NOx sensor regarding the exhaust Dew Point. The downstream NOx sensor's integrated control module times out because it stops receiving the required Dew Point Message from the ECM, causing the sensor to drop back to a standby temperature and stop measuring NOx levels.

• Tier 4b
• Steiger
• Magnum
• Maxxum
• Puma
• Quadtrac
• Axial-Flow

1. 1

   Check exhaust temperature sensors using an Electronic Service Tool (EST) to verify accurate readings. If the ECM thinks the exhaust is too cold, it will never send the message.

2. 2

   Inspect the CAN bus wiring harness between the ECM and the downstream NOx sensor for chafing, corrosion, or loose pins.

3. 3

   Verify the downstream NOx sensor is receiving proper voltage and has a solid ground.

4. 4

   Inspect the muffler and exhaust piping for damage or leaks that could prevent the system from reaching the required 120°C+ operating temperature.

5. 5

   Look for other active CAN communication faults or exhaust temperature faults (e.g., SPN 3238 / 3240 for Aftertreatment Exhaust Dew Point Message).

1. 1

   Power Down

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

2. 2

   Harness Repair

   If diagnostic checks revealed damaged wiring between the ECM and the NOx sensor connector, repair the wiring harness and replace any corroded connector pins.

3. 3

   Replace the Sensor

   If the wiring, power, ground, and exhaust temperatures are all within specification, the NOx sensor's internal communication module has likely failed. Disconnect the downstream NOx sensor from the exhaust pipe and the wiring harness, and install a new OEM sensor. (Note: The electronic control unit on the sensor cannot be separated from the sensor element; the entire unit must be replaced).

4. 4

   Reassemble and Clear Codes

   Reconnect the battery. Connect the Case IH Electronic Service Tool (EST) and clear the inactive fault codes.

5. 5

   Verification Drive Cycle

   Run the engine under load (or perform a stationary forced regeneration) until the exhaust temperature reaches at least 150°C. This forces the ECM to calculate the dew point, send the Dew Point Message, and verify that the downstream NOx sensor responds and begins measuring.