Case IH 19019 (DTC 1A1A) - ECU – DCU (Dosing Control Unit) or Engine ECU (ENG): Upstream SCR catalyst temperature sensor voltage is higher than expected

Indicates an open circuit (broken wire or failed internal thermistor) or a short to a high-voltage source within the sensor circuit.

• MAXXUM T4E
• 240 Series Axial-Flow Combines
• Steiger Series (350 to 600 HP, including Rowtrac and QT models)
• Magnum Series (235 – 340, Series 4)
• Puma and Farmall series (40-45-50 with CVT)

1. 1

   Perform a plausibility check using an Electronic Service Tool to read live temperature data from the upstream catalyst sensor on a cold engine (should roughly match ambient temperature).

2. 2

   Inspect the wiring harness and connectors between the upstream SCR temperature sensor and the DCU for broken wires (open circuit), chafing, or a short to power.

3. 3

   Ensure the sensor is installed correctly and check the exhaust gas piping and muffler for physical damage that could impact sensor readings.

1. 1

   Inspect Wiring First

   Thoroughly inspect the wiring harness and the connector at the sensor. Repair any broken wires or clean any corroded pins.

2. 2

   Replace the Sensor

   If no faults are found in the wiring harness or connections, the internal thermistor of the sensor has likely failed open. Remove and replace the upstream SCR catalyst temperature sensor.

3. 3

   Module Verification

   If the error persists after replacing the sensor and verifying the harness, the fault may lie internally within the DCU/Pump Module, which would then require replacement.

4. 4

   Clear Codes

   Use the Electronic Service Tool to clear the fault codes and run the engine to verify that the sensor voltage has returned to the normal operating range.