Case IH 19010 (DTC 161A) - ECU – DCU (Dosing Control Unit) or Engine ECU: Downstream SCR catalyst temperature sensor voltage is higher than expected

The control module is receiving a voltage signal from the downstream exhaust gas temperature sensor that exceeds the maximum programmed threshold. In 5-volt reference sensor circuits, a 'voltage high' condition almost always indicates an open circuit, typically caused by a disconnected plug, a broken wire in the harness, or an internal failure (open thermistor) within the sensor itself.

• MAXXUM T4E
• Case IH 240 Series Axial-Flow Combines
• Case IH Magnum 235 – 340 (Series 4) Tractors
• Case IH Steiger Tractors (350 to 600 HP)

1. 1

   Inspect the wiring harness leading to the downstream SCR catalyst temperature sensor for chafed wires, melted insulation from exhaust heat, or physical damage.

2. 2

   Disconnect the sensor's electrical connector and check for moisture, corrosion, or pushed-back pins.

3. 3

   Use a multimeter to measure the resistance across the sensor's pins. An infinite resistance reading (OL) confirms the sensor has failed internally (open circuit).

4. 4

   Connect the Case IH Electronic Service Tool (EST) laptop to monitor live data for the downstream SCR temperature and check for secondary codes (such as code 3589).

1. 1

   Cool Down

   Ensure the machine is turned off and the exhaust/SCR system has completely cooled down to prevent severe burns.

2. 2

   Locate the Sensor

   Locate the downstream temperature sensor, which is threaded into the exhaust pipe after the SCR catalyst chamber.

3. 3

   Disconnect

   Unplug the sensor's electrical connector from the main machine harness.

4. 4

   Remove the Sensor

   Carefully unscrew the sensor from the exhaust pipe. Note: Exhaust sensors are prone to seizing. Apply penetrating oil to the threads and allow it to soak if the sensor is stuck.

5. 5

   Install the New Sensor

   Thread the new downstream temperature sensor into the exhaust pipe and tighten it to the manufacturer's torque specification.

6. 6

   Reconnect

   Plug the electrical connector back into the harness, ensuring the locking tab clicks into place.

7. 7

   Clear Codes and Reset

   Use the Case IH EST (Electronic Service Tool) laptop to clear the inactive fault codes and reset the SCR system.