Case IH 19828 – Engine Control Unit (ECU): Upstream oxidation catalyst temperature is too low

This fault code indicates that the temperature reading from the sensor located just before the Diesel Oxidation Catalyst (DOC) in the exhaust aftertreatment system is falling below the expected physical limit or the ECU's calculated temperature value. This can prevent the aftertreatment system from functioning correctly, as proper temperatures are required for emissions reduction.

• Tier 4b
• Steiger 535
• Steiger 580
• Magnum 310
• Puma
• Farmall
• Austoft 9900
• N-Series Loaders
• 621G
• 721G

1. 1

   Verify Fault Status: Use the electronic service tool (EST or PT-Box) to verify if the fault is currently active or stored in history.

2. 2

   Visual Inspection: Inspect the DOC upstream temperature sensor to ensure it is physically installed and mounted correctly in the exhaust pipe.

3. 3

   Wiring and Connector Check: Inspect the sensor's wiring harness and the 2-wire connector (often designated as C189 or X189) for damage, corrosion, open circuits, or short circuits to ground/battery.

4. 4

   Resistance Test: Unplug the sensor and measure its resistance with a multimeter to verify if it has failed internally (open circuit).

5. 5

   System Plausibility: Check for exhaust leaks upstream of the DOC or a faulty engine thermostat that might be preventing the exhaust gases from reaching normal operating temperatures.

1. 1

   Turn off the engine, remove the key, and disconnect the battery power to protect the electronic systems.

2. 2

   Locate the DOC upstream temperature sensor on the exhaust aftertreatment assembly.

   It is situated directly before the Diesel Oxidation Catalyst (DOC).

3. 3

   Disconnect the 2-wire electrical harness connector from the sensor.

4. 4

   Carefully unscrew and remove the faulty temperature sensor from the exhaust pipe.

5. 5

   Install the new DOC upstream temperature sensor and tighten it to the OEM specified torque.

   Refer to the specific engine's manual for exact torque values, generally around 25-35 Nm for exhaust temperature sensors.

6. 6

   Reconnect the electrical harness connector securely.

7. 7

   Reconnect battery power, connect the diagnostic service tool, clear the inactive fault codes, and run the engine to verify that the upstream DOC temperature reading is now plausible and the code does not return.