Case IH F-3216-02 - ECU – Engine Control Unit (ECU): Upstream NOx sensor values are not plausible

The engine control system is receiving a signal from the NOx sensor located before the SCR/DPF catalyst that fluctuates abnormally or does not align with the expected engine operating parameters and exhaust output.

• MAGNUM AFS Connect
• 240 Series Axial-Flow Combines
• Magnum Tractors 180, 200, 220, 240, 250, 280, 310, 340, 380
• Steiger 4WD & 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

   Check the CAN bus wiring harness leading to the upstream NOx sensor module for chafing, shorts to ground, or open circuits.

2. 2

   Verify the power supply and ground to the NOx sensor module, as a loss of power or voltage drops can trigger erratic data.

3. 3

   Inspect the exhaust pipe upstream of the NOx sensor for leaks, as unmetered air entering through a cracked pipe or loose flange can cause implausible readings.

4. 4

   Look for other active codes (such as SPN 3216 FMI 12 or FMI 9) which might help isolate a wiring issue from a failed sensor element.

1. 1

   Preparation

   Power down the machine, turn off the battery isolator switch, and allow the exhaust system to cool completely.

2. 2

   Locate the Sensor

   Locate the Upstream NOx sensor (Aftertreatment #1 Intake NOx sensor), which is mounted in the exhaust pipe before the DPF/SCR assembly.

3. 3

   Disconnect

   Unplug the electrical connector at the NOx sensor control module. Inspect the pins for corrosion or moisture.

4. 4

   Removal

   Using a specialized NOx sensor socket or a wrench, carefully remove the sensor probe from the exhaust pipe. (Penetrating oil may be required if the threads are seized).

5. 5

   Installation

   Install the new NOx sensor. If the new sensor does not have pre-applied anti-seize on the threads, apply a high-temperature anti-seize compound (be extremely careful not to get any on the sensor tip). Torque to OEM specifications.

6. 6

   Routing

   Mount the sensor control module and route the wiring harness exactly as it was from the factory, ensuring it is secured away from extreme heat sources and moving parts.

7. 7

   Calibration/Reset

   Reconnect the battery, turn the key on, and use a diagnostic service tool (like the CNH Electronic Service Tool) to clear the inactive fault codes. Some systems may require an aftertreatment reset or a stationary regeneration to validate the repair.