Case IH 19188 (DTC 22CE) - ECU – Engine Control Unit (ECU) / Engine Management System (EMS): Upstream NOx sensor self-diagnosis result is lower than the limit.

The upstream NOx sensor is located in the exhaust stream before the Diesel Oxidation Catalyst (DOC). Its job is to measure the raw level of Nitrogen Oxide pollutants and unburned fuel coming directly from the engine's combustion chambers. This code triggers when the sensor's internal self-diagnostic check returns a value below the minimum acceptable threshold. This typically indicates an internal failure of the sensor, heavy soot contamination/poisoning of the sensor tip, or an exhaust leak diluting the exhaust gases before they reach the sensor.

• MAXXUM T4E
• 240 Series Axial-Flow (7240, 8240, 9240)
• Magnum (180, 200, 220, 240, 250, 280, 310, 340)
• Puma (150, 165)
• Steiger (e.g., 580)
• N-Series Loader Backhoes

1. 1

   Inspect the wiring harness and Connector C186 leading to the upstream NOx sensor for chafing, melting, or corrosion (a voltage drop or poor connection can cause lower-than-expected values)

2. 2

   Inspect the exhaust manifold and piping between the engine block and the DOC for exhaust leaks (leaks introduce fresh air or allow exhaust to escape, dropping NOx concentration readings)

3. 3

   Check for other active codes related to fuel injection timing, engine misfires, or intake manifold temperatures (these can alter raw engine emissions and trigger a false NOx code)

4. 4

   Verify with a dealer diagnostic tool if there is an ECU software update available to adjust overly sensitive NOx sensor logic

1. 1

   Preparation

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

2. 2

   Disconnect Power

   Disconnect the negative battery cable to prevent electrical shorts or accidental ECU damage during the repair.

3. 3

   Locate the Sensor

   Locate the upstream NOx sensor in the exhaust pipe, positioned before the Diesel Oxidation Catalyst (DOC).

4. 4

   Disconnect Wiring

   Unplug the 5-pin electrical connector (C186) from the machine's wiring harness. Unclip the wire from any heat shields or retaining brackets.

5. 5

   Remove the Sensor

   Using a 22mm NOx sensor socket or a specialized line wrench, carefully unscrew the sensor from the exhaust bung. If it is seized, apply penetrating oil and allow it to soak.

6. 6

   Clean the Threads

   Use a thread chaser to clean the threads in the exhaust pipe bung to ensure the new sensor seats correctly.

7. 7

   Install the New Sensor

   Apply a small amount of high-temperature, sensor-safe anti-seize compound to the threads of the new sensor (if it does not come pre-coated). Caution: Do not get any anti-seize on the sensor probe itself, as this will ruin it. Thread the sensor in by hand to prevent cross-threading, then torque to the manufacturer's specification (typically around 37 lb-ft / 50 Nm).

8. 8

   Reconnect

   Plug the 5-pin connector back into the harness and secure the wire away from extreme heat sources.

9. 9

   Clear Codes

   Reconnect the battery. Turn the ignition on and use a diagnostic scan tool to clear the 19188 (DTC 22CE) fault code.

10. 10

    Validation

    Start the engine and allow it to reach operating temperature. Perform a forced stationary regeneration or a test drive under load to ensure the code does not return.