Case IH 19010 – DCU (Dosing Control Unit): Temperature sensor after catalyst (electrical) – signal high – P042D Catalyst Temperature Sensor Circuit High

The control module is receiving an abnormally high voltage signal from the exhaust gas temperature sensor located downstream (after) the SCR catalyst, indicating an open circuit, a failed sensor with an internal open, or a short to a power source.

• Tier 4a
• Tier 4b
• Magnum (235–340 Series 4)
• Puma (130–240)
• Steiger (350–620)
• Quadtrac (370–620)
• Maxxum (120–150)
• Farmall (100C–140A)
• Axial-Flow 5130
• Axial-Flow 7130
• Axial-Flow 7230
• Axial-Flow 8230
• Axial-Flow 9230
• Axial-Flow 9250

1. 1

   Visual Inspection: Inspect the wiring harness running from the post-catalyst temperature sensor to the DCU. Look for chafed wires, melted insulation from exhaust heat, or severed connections.

2. 2

   Connector Check: Disconnect the sensor and inspect the pins on both the sensor side and the harness side. Look for corrosion, moisture, or pushed-out pins.

3. 3

   Resistance/Continuity Testing: Use a multimeter to measure the resistance across the sensor's terminals. An 'OL' (Open Loop) or infinite resistance reading confirms the sensor has failed internally.

4. 4

   Harness Testing: With the sensor unplugged, turn the key ON and check the harness side for proper reference voltage and ground to rule out a short-to-power in the main wiring harness.

5. 5

   Live Data Verification: Use an Electronic Service Tool (EST) to view the live data for the 'Temperature sensor after catalyst.' If it reads a default maximum value (or an implausible extreme temperature), it confirms the open circuit.

1. 1

   Power Down

   Turn off the machine, remove the key, and turn off the battery disconnect switch to ensure the DCU is powered down.

2. 2

   Locate the Sensor

   Locate the exhaust gas temperature sensor positioned on the exhaust pipe after (downstream of) the SCR catalyst.

3. 3

   Remove the Sensor

   Disconnect the electrical pigtail. Using an appropriately sized wrench or sensor socket, carefully unthread the sensor from the exhaust pipe. (Penetrating oil may be required if the sensor is seized from exhaust heat).

4. 4

   Install the New Sensor

   Thread the new OEM temperature sensor into the exhaust bung. Tighten it to the manufacturer's specified torque to prevent damaging the threads.

5. 5

   Reconnect

   Plug the sensor's electrical connector back into the machine's wiring harness, ensuring the locking tab clicks into place.

6. 6

   Clear Codes

   Turn the battery disconnect back on and turn the ignition key to the ON position. Connect your diagnostic tool to the universal controller/DCU and clear the stored 19010 (P042D) fault code.

7. 7

   Test Operation

   Start the engine and monitor the exhaust temperature live data to ensure the new sensor is reading plausibly and the fault code does not return.