Case IH 19570 – Engine Control Module (ECM) or Vehicle Control Module (VCM): Plausibility error during Rich to Lean switch over

This is an emissions-related fault indicating that during the transition from a rich exhaust state (higher fuel/lower oxygen) to a lean exhaust state (lower fuel/higher oxygen), the exhaust gas sensors (NOx sensor or Lambda/O2 sensor) did not detect the expected change in exhaust gas composition. Triggered when the sensor response is sluggish, delayed, or out of the expected range.

• Tier 4b
• Magnum series (180 through 370)
• Steiger and Quadtrac series (350 through 600)
• Puma series (150, 165, etc.)
• Maxxum series
• Axial-Flow series (5130/5140, 6130/6140, 7130/7140, 8230/8240, 9230/9240)
• Patriot Sprayers (2250, 3240, 3340, 4440)
• Titan Floaters (3030/3040, 3530/3540, 4030/4040)
• N-Series Loader Backhoes
• heavy wheel loaders (521F through 921F)

1. 1

   Check for any exhaust leaks upstream of the SCR catalyst and the NOx/Lambda sensors, which can introduce unmetered oxygen and skew readings.

2. 2

   Inspect the wiring harness and the 5-pin/6-pin connectors going to the NOx and Lambda sensors for chafed wires, melted insulation, or corrosion inside the pins.

3. 3

   Ensure the DEF dosing system is operating correctly. Check for poor DEF quality or a partially clogged DEF injector causing abnormal exhaust chemistry.

4. 4

   Using the CNH Electronic Service Tool (EST), monitor the live data of the NOx and Lambda sensors during an active regeneration or test cycle to see if the sensor voltage/ppm readings are stuck or responding too slowly.

1. 1

   Locate the Sensor

   Identify the faulty sensor on the exhaust aftertreatment pipe (usually the NOx sensor upstream/downstream of the SCR catalyst).

2. 2

   Remove the Sensor

   Disconnect the sensor's electrical connector. Use a specialized O2/NOx sensor socket to carefully unthread the sensor from the exhaust pipe. Apply penetrating oil if the sensor is seized to avoid stripping the exhaust bung threads.

3. 3

   Install the New Sensor

   Apply a small amount of anti-seize compound to the threads of the new sensor (if not already pre-applied by the manufacturer). Thread it in by hand to prevent cross-threading, then torque to the OEM specification.

4. 4

   Reconnect Wiring

   Plug the sensor connector back into the machine's harness, ensuring the locking tab clicks into place.

5. 5

   Software Reset

   Connect the CNH EST diagnostic tool. Clear the 19570 fault code. You must reset the learned values for the NOx/Lambda sensor in the ECM so the system can calibrate to the new sensor.

6. 6

   Validation

   Run the engine through a complete warm-up cycle and perform a stationary emissions test to verify the rich-to-lean switchover is now reading correctly and the code does not return.