Case IH 19042 (DTC 372C) - ECU – Engine ECU: Downstream SCR temperature sensor comparison to a calculated temperature value failure.

The engine management system continuously calculates an expected exhaust gas temperature downstream of the Selective Catalytic Reduction (SCR) catalyst based on current engine load, speed, and upstream sensor data. If the actual temperature reported by the downstream SCR temperature sensor deviates significantly from this calculated model, the system logs this fault. This can be triggered by a failing temperature sensor, abnormal exhaust temperatures caused by engine issues, exhaust leaks, or DEF (AdBlue) system malfunctions.

• MAXXUM T4E
• Case IH 240 Series Axial-Flow® Combines (e.g., 7240, 8240, 9240)
• Other Case IH and New Holland tractors/equipment sharing the same FPT (Fiat Powertrain Technologies) Tier 4/Stage V engine architecture

1. 1

   Inspect the downstream SCR temperature sensor connector wiring. Verify Pin 1 has a 5-volt supply from the ECU and Pin 2 has a good common ground to the ECU.

2. 2

   Check for any exhaust leaks between the engine and the SCR catalyst, which can introduce cool air and artificially lower the temperature reading.

3. 3

   Check if the DEF return tube is free and unobstructed, as abnormal temperatures can be caused by DEF fluid delivery issues.

4. 4

   Ensure the reflux tube inside the DEF tank is not clogged.

5. 5

   Use a diagnostic tester to command the DEF reversing valve. Ensure it is functioning properly and is not stuck in the closed position.

1. 1

   Preparation

   Ensure the machine is parked on a level surface, the engine is off, and the exhaust system has completely cooled down to prevent severe burns.

2. 2

   Locate the Sensor

   Locate the downstream SCR temperature sensor on the exhaust pipe, positioned after the SCR catalyst chamber.

3. 3

   Disconnect Harness

   Unplug the sensor's electrical connector from the main engine wiring harness.

4. 4

   Remove the Sensor

   Using an appropriate wrench or sensor socket, carefully unthread the temperature sensor from the exhaust pipe. (Note: Penetrating oil may be required if the sensor is seized from exhaust heat).

5. 5

   Install the New Sensor

   Apply a small amount of high-temperature anti-seize compound to the threads of the new sensor (if it does not come pre-applied). Thread it into the exhaust pipe and tighten to the OEM torque specification.

6. 6

   Reconnect

   Plug the sensor's electrical connector back into the wiring harness.

7. 7

   Clear Codes & Test

   Connect your diagnostic service tool, clear the 19042 (372C) fault code, and start the engine. You may need to perform a stationary (forced) regeneration or run the machine under load to verify that the exhaust temperatures read correctly and the code does not return.