Case IH 19011 (DTC 271A) - ECU – DCU (Dosing Control Unit) or Engine ECU (EDC): Downstream SCR catalyst temperature sensor voltage is lower than expected

The control module is receiving a voltage signal from the exhaust gas temperature sensor located after the Selective Catalytic Reduction (SCR) catalyst that falls below the minimum acceptable threshold. This usually points to a short to ground in the sensor circuit, a failed sensor element, or a severely damaged wiring harness.

• MAXXUM T4E
• 240 Series Axial-Flow (7240, 8240, 9240)
• Magnum 235-340 series
• Steiger 350-600 series
• Farmall CVT models (40-45-50, 115U, 120A)
• 580N EP Backhoe Loaders

1. 1

   Visual Inspection: Inspect the wiring harness leading to the downstream SCR catalyst temperature sensor for melted, chafed, or shorted wires.

2. 2

   Connector Check: Disconnect the sensor pigtail and check for melted plastic, water intrusion, or corroded pins.

3. 3

   Voltage/Ground Test: Turn the key to the ON position (engine off) and use a multimeter to verify the 5V reference signal and ground at the harness-side connector.

4. 4

   Sensor Resistance Test: Measure the resistance across the sensor pins to check for an open circuit (infinite resistance) or a dead short (0 ohms).

1. 1

   Preparation

   Ensure the machine has been turned off and the exhaust system has completely cooled down to prevent severe burns. Disconnect the negative battery cable.

2. 2

   Locate the Sensor

   Locate the SCR catalyst canister in the exhaust system. Identify the downstream temperature sensor (located after the catalyst, closer to the tailpipe).

3. 3

   Disconnect

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

4. 4

   Removal

   Spray the sensor threads with penetrating oil and let it sit (exhaust sensors are notoriously prone to seizing). Carefully remove the sensor using a specialized exhaust temperature sensor socket or a flare-nut wrench to avoid stripping the hex.

5. 5

   Installation

   Apply a small amount of high-temperature anti-seize compound to the threads of the new sensor (if it doesn't come pre-applied). Caution: Do not get any anti-seize on the sensor probe tip, as this will ruin the sensor.

6. 6

   Torque

   Thread the sensor in by hand to prevent cross-threading, then tighten to the OEM torque specification.

7. 7

   Reconnect

   Plug the electrical connector back into the harness, ensuring the locking tab clicks into place. Secure the wire away from direct heat sources using high-temp zip ties if necessary.

8. 8

   Clear Codes

   Reconnect the battery. Use the Case IH Electronic Service Tool (EST) or a compatible heavy-duty OBD scanner to clear the inactive 19011 / 271A fault code. Run the engine and verify the code does not return.