Case IH 19186 (F-3224-31) - ECU – Engine Control Module (ECM) or Vehicle Control Module (VCM): Upstream NOx sensor has too often aborted its self-diagnosis check during afterrun

When the engine is shut down, the emissions system enters an 'afterrun' phase where it performs self-diagnostic checks on the emissions sensors. This code indicates that the upstream Nitrogen Oxide (NOx) sensor failed to complete this self-check multiple times. This is typically caused by implausible sensor readings, temperature instability, excessive soot buildup on the sensor element, or an internal failure of the sensor itself.

• VESTRUM CVX
• 580N
• 580 Super N (580SN)
• 580SN WT
• 590SN
• Magnum 180
• Magnum 200
• Magnum 220
• Magnum 240
• Magnum 250
• Magnum 280
• Magnum 310
• Magnum 340
• Puma 150
• Puma 165
• 5140
• 6140
• 7140
• 7240
• 8240
• 9240
• Patriot 2250
• Patriot 3240
• Patriot 3340
• Patriot 4440
• Titan series

1. 1

   Inspect the exhaust piping upstream of the SCR catalyst for leaks that can introduce fresh air or alter pressures, skewing the NOx sensor readings.

2. 2

   Check the upstream NOx sensor wiring harness and connector for chafing, melting, corrosion, or loose pins.

3. 3

   Verify that the upstream and downstream exhaust temperature sensors are reading accurately (typically 220°C - 240°C), as faulty temperature data can prevent the NOx sensor from completing its checks.

4. 4

   Remove the sensor and visually inspect for heavy soot or DEF crystallization on the tip, which can insulate the element.

1. 1

   Preparation

   Park the machine on a level surface, turn off the engine, and allow the exhaust system to cool completely to prevent severe burns.

2. 2

   Locate the Sensor

   Locate the upstream NOx sensor. It is threaded into the exhaust pipe before the Diesel Oxidation Catalyst (DOC) and SCR catalyst assembly.

3. 3

   Disconnect Wiring

   Carefully unplug the electrical connector for the upstream NOx sensor from the main engine wiring harness.

4. 4

   Remove the Sensor

   Using an appropriate NOx sensor socket or wrench (typically 22mm or 7/8"), unscrew the sensor from the exhaust bung.

5. 5

   Install the New Sensor

   Apply a small amount of high-temperature anti-seize compound to the threads of the new sensor (if not already pre-applied). Caution: Do not get any anti-seize on the sensor tip. Thread the sensor in by hand to prevent cross-threading, then tighten to the OEM torque specification.

6. 6

   Reconnect and Route

   Reconnect the electrical connector. Ensure the wiring pigtail is routed away from extreme heat sources and secured with zip ties if necessary.

7. 7

   Clear Codes

   Turn the ignition on and use a dealer diagnostic tool (such as the Case Electronic Service Tool) to clear the fault codes and reset any learned values for the new NOx sensor.