Case IH 19571 – Engine Control Module (ECM) or Vehicle Control Module (VCM): Monitoring of NOx signal readiness

This code indicates that the engine's aftertreatment control system is unable to verify the readiness or plausibility of the Nitrogen Oxide (NOx) sensor signal within the expected timeframe. If the sensor fails to reach a 'ready' state, the system cannot guarantee emissions compliance.

• Tier 4b
• 580N
• 580SN
• 580SN WT
• 590SN
• Magnum Tractors (180-340)
• Puma Tractors (150-165)
• Axial-Flow Combines (5140-9240)
• Patriot Sprayers

1. 1

   Check for accompanying circuit-specific NOx codes (e.g., 19572, 19573, 19574, 19575) which indicate a hard electrical failure rather than a readiness timeout.

2. 2

   Inspect the wiring harness and connectors leading to the NOx sensor module for chafing, heat damage, corrosion, and moisture.

3. 3

   Check for exhaust leaks upstream of the NOx sensor, which can introduce unmetered oxygen or allow exhaust gases to escape.

4. 4

   Verify DEF quality, as contaminated or degraded DEF can cause poor NOx conversion that the sensor interprets as a failure to reach readiness.

5. 5

   Test power and ground to verify the NOx sensor module is receiving proper voltage (12V or 24V) and has a solid ground.

1. 1

   Power Down

   Turn off the machine and disconnect the battery to prevent electrical shorts and ensure safety.

2. 2

   Locate the Sensor

   Locate the affected NOx sensor on the SCR exhaust pipe. Verify which sensor is failing via your diagnostic tool if the system has both upstream and downstream sensors.

3. 3

   Disconnect

   Unplug the electrical connector from the NOx sensor's control module.

4. 4

   Remove the Sensor

   Use a specialized NOx sensor socket or a 22mm wrench to carefully remove the sensor probe from the exhaust pipe. Apply penetrating oil if the sensor is seized from heat cycling.

5. 5

   Install the New Sensor

   Apply a high-temperature anti-seize compound to the threads of the new NOx sensor (if not already pre-applied). Thread it into the exhaust pipe and torque to OEM specifications.

6. 6

   Route Wiring

   Securely mount the sensor's control module and route the wiring away from extreme heat sources or sharp edges. Reconnect the electrical plug.

7. 7

   Clear Codes and Test

   Reconnect the battery. Connect a diagnostic laptop (such as the CNH Electronic Service Tool) to clear the 19571 fault code.

8. 8

   Validation

   Run the engine up to operating temperature and perform an SCR system test or a forced manual regeneration. Verify that the NOx sensor reaches readiness and the fault code does not return.