Case IH 19569 – Engine Control Module (ECM) or Dosing Control Unit (DCU): NOx offset signal plausibility check

The baseline (offset) reading from the Nitrogen Oxide (NOx) sensor is out of the expected range or is implausible when compared to other sensor data.

• Tier 4b
• Magnum 180
• Magnum 220
• Magnum 240
• Magnum 250
• Magnum 310
• Steiger
• Puma
• Maxxum
• Optum
• 7240 Combine
• 8240 Combine
• Patriot 2250 Sprayer
• Titan Floaters
• Case N-Series Loader Backhoes

1. 1

   Check for accompanying NOx sensor codes (e.g., 3528, 3529, 3530, 3533, 19784) which might indicate a hard electrical failure, CAN timeout, or general SCR failure

2. 2

   Inspect the wiring harness and the 5-pin MCON connector at the NOx sensor for corrosion, moisture, or damaged pins

3. 3

   Verify power and CAN communication to ensure the sensor is receiving proper voltage and has a solid ground

4. 4

   Check for exhaust leaks upstream of the NOx sensor, as unmetered air can skew readings and trigger a plausibility error

5. 5

   Perform a DEF system check to ensure fluid is uncontaminated and the doser/injector is not leaking

1. 1

   Disconnect battery

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

2. 2

   Repair wiring

   If wiring damage is found during the diagnostic phase, repair the harness or replace the connector pigtail.

3. 3

   Determine sensor replacement

   If the wiring and exhaust system are intact, the NOx sensor's internal sensing element has likely degraded and the sensor must be replaced.

4. 4

   Locate sensor

   Locate the faulty NOx sensor (typically the downstream sensor located behind the SCR catalyst).

5. 5

   Remove sensor

   Disconnect the 5-pin electrical connector and carefully unscrew the NOx sensor from the exhaust pipe.

6. 6

   Install new sensor

   Apply a high-temperature anti-seize compound to the threads of the new sensor (if not pre-applied by the manufacturer) and install it into the exhaust pipe. Tighten to the manufacturer's specified torque.

7. 7

   Reconnect wiring

   Reconnect the electrical connector and secure the wiring harness away from extreme heat sources.

8. 8

   Reconnect battery

   Reconnect the battery.

9. 9

   Clear codes and reset offset

   Connect the CNH EASy diagnostic tool (or an equivalent heavy-duty scanner) to clear the fault codes and reset the NOx sensor learned offset values.

10. 10

    Verify repair

    Run the machine through a standard operating cycle to verify the code does not return.