Case IH 19011 – DCU (Dosing Control Unit): Temperature sensor after catalyst (electrical) | signal low | Catalyst Temperature Sensor Circuit Low

The control module is receiving a voltage signal from the downstream SCR catalyst temperature sensor that is below the acceptable minimum threshold, indicating a short circuit to ground, an open circuit in the sensor wiring, or a completely failed temperature sensor.

• Tier 4a
• Tier 4b
• Magnum Series 235
• Magnum Series 260
• Magnum Series 290
• Magnum Series 315
• Magnum Series 340 (Series 4)
• Steiger Series 350
• Steiger Series 400
• Steiger Series 450
• Steiger Series 500
• Steiger Series 550
• Steiger Series 600
• Puma Series

1. 1

   Visually inspect that the downstream temperature sensor is installed correctly in the exhaust tube after the catalyst.

2. 2

   Inspect the muffler and exhaust gas piping for physical damage, leaks, or incorrect mounting, which can cause skewed temperature readings.

3. 3

   Inspect the sensor's electrical connector and the wiring harness routing back to the DCU for chafed wires, moisture in the connector, open circuits, or a short to ground.

4. 4

   Use an Electronic Service Tool (EST) to check the temperature ratio between the upstream and downstream catalyst sensors. If the downstream sensor reads statically low while the upstream sensor reads normal, it is likely defective.

1. 1

   Disconnect Power

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

2. 2

   Repair Wiring

   If the diagnostic checks revealed a short or break in the wiring harness between the sensor and the DCU, repair the wiring or replace the affected harness section.

3. 3

   Replace the Sensor

   If the wiring is intact, the sensor itself has failed internally. Disconnect the electrical pigtail of the temperature sensor located after the SCR catalyst.

4. 4

   Remove the Old Sensor

   Carefully unthread the sensor from the exhaust piping (use penetrating oil if the exhaust heat has seized the threads).

5. 5

   Install the New Sensor

   Thread the new sensor into the exhaust pipe and tighten to OEM torque specifications. Reconnect the electrical harness.

6. 6

   Clear Codes and Test

   Reconnect the battery. Connect the Electronic Service Tool (EST), clear the 19011 / P042C fault code, and execute a DeNOx System Test with the tester to verify the new sensor is reading correctly and the fault does not return.