Case IH F-3224-02 - ECU – Engine Control Unit (ECU): Upstream NOx sensor lambda signal deviation - NOx sensor possible removal detected

The upstream NOx sensor measures the level of pollutants and unburned fuel coming directly from the combustion chambers. The system continuously monitors the lambda (oxygen) signal from this sensor. If the sensor reports a value that deviates drastically from the engine's expected modeled parameters (e.g., reading excessive oxygen as if it were exposed to free air), the system flags it as a severe signal deviation or assumes the sensor has been physically removed from the exhaust pipe.

• MAGNUM AFS Connect
• Magnum Tractors: 180, 200, 220, 240, 250, 280, 310, 340
• Puma Tractors: 150, 165, and CVX models
• Steiger Tractors
• Farmall Tractors: 40, 45, 50
• Axial-Flow Combines (240 Series): 5140, 6140, 7140, 7240, 8240, 9240
• Patriot Sprayers: 2250, 3240, 3340, 4440
• Titan Floaters: 3040, 3540, 4040, 4540

1. 1

   Verify that the upstream NOx sensor is physically installed in the exhaust pipe before the DOC and is tightened securely.

2. 2

   Inspect the exhaust manifold and piping upstream of the sensor for cracks, blown gaskets, or loose clamps that could introduce fresh air into the exhaust stream.

3. 3

   Check the sensor's 5-pin electrical connector (C186 or X186) for backed-out terminals, corrosion, or melted wiring.

4. 4

   Verify the sensor is receiving the correct supply voltage (12V or 24V depending on the machine's electrical system).

1. 1

   Turn off the machine's ignition and disconnect the battery to prevent electrical shorts.

   Ensure the machine is powered down before beginning work.

2. 2

   Locate the upstream NOx sensor in the exhaust pipe before the DOC.

   Identify the sensor location for removal.

3. 3

   Disconnect the sensor's 5-pin electrical connector (C186/X186) from the main engine harness.

   Unplug the sensor from the electrical system.

4. 4

   Carefully unthread the NOx sensor from the exhaust pipe (it uses an M20 x 1.5 thread).

   Use penetrating oil if the sensor is seized to avoid damaging the exhaust bung threads.

5. 5

   Install the new upstream NOx sensor.

   If the new sensor does not have pre-applied anti-seize on the threads, apply a high-temperature exhaust anti-seize compound. Torque to the manufacturer's specification.

6. 6

   Route the sensor's pigtail cable (typically ~600mm long) away from extreme heat sources and moving parts, then plug it into the harness.

   Ensure the cable is safely routed to prevent future damage.

7. 7

   Reconnect the battery.

   Restore power to the machine.

8. 8

   Connect a diagnostic tool (such as the CNH Electronic Service Tool) to clear the F-3224-02 / 19061 fault code.

   Clear the logged fault code from the ECU.

9. 9

   Run the engine up to operating temperature or perform a forced aftertreatment system test.

   Verify the lambda signal is reading correctly and the code does not return.