Case IH 19180 – Engine Management System (EMS) / Engine Control Module (ECM): Downstream NOx sensor self-diagnosis result is lower than the limit.

The downstream Nitrogen Oxide (NOx) sensor is returning an implausibly low value or failing its internal diagnostic threshold, indicating the sensor itself is likely faulty or heavily degraded.

• Tier 4b
• 240 Series Axial-Flow Combines (5140, 6140, 7140, 7240, 8240, 9240)
• Magnum Tractors (180, 200, 220, 240, 250, 280, 310, 340, 380)
• Steiger / Quadtrac Tractors (370, 420, 470, 500, 540, 580, 620)
• Puma Tractors (150, 165, 185, 200, 220)
• Maxxum Tractors (115, 125, 135, 145, 150)
• Farmall Tractors (110A, 120A, 130A, 140A)

1. 1

   Inspect the wiring harness and the electrical connector for the downstream NOx sensor for chafed wires, melted insulation, corrosion, or loose pins

2. 2

   Check the exhaust system for leaks, particularly around the SCR catalyst and the NOx sensor mounting bung

3. 3

   Read out all DTCs to verify if there are other codes present (such as upstream NOx sensor codes like 19187/19188 or DEF dosing faults)

4. 4

   Remove the sensor and inspect the probe for excessive soot buildup, moisture damage, or physical impact damage

1. 1

   Preparation

   Ensure the machine is parked on a level surface, the engine is turned off, and the exhaust system has completely cooled down to prevent severe burns. Disconnect the battery.

2. 2

   Locate the Sensor

   Find the downstream NOx sensor, which is mounted in the exhaust pipe directly after the SCR catalyst.

3. 3

   Disconnect Wiring

   Carefully unplug the electrical connector linking the NOx sensor module to the machine's main wiring harness.

4. 4

   Remove the Sensor

   Using a specialized NOx/O2 sensor socket (usually 22mm) or a suitable wrench, loosen and remove the NOx sensor from the exhaust bung.

5. 5

   Prepare the New Sensor

   Check the threads of the new NOx sensor. If it does not have anti-seize compound pre-applied, apply a small amount of high-temperature exhaust anti-seize to the threads (strictly avoiding the sensor tip, as this will contaminate it).

6. 6

   Install the New Sensor

   Thread the new sensor into the exhaust bung by hand to prevent cross-threading, then tighten it to the manufacturer's specified torque.

7. 7

   Reconnect Wiring

   Plug the electrical connector back into the harness, ensuring it clicks securely into place. Route the wire exactly as it was from the factory to avoid heat damage.

8. 8

   Reconnect Battery

   Reconnect the machine's battery.

9. 9

   Clear Codes and Reset

   Connect a diagnostic tool (such as the Case IH Electronic Service Tool - EST) to clear the fault code 19180 (DTC 2DBE). Perform any required SCR system resets or NOx sensor initialization procedures as prompted by the software to validate the repair.