Case IH 19068 – Engine Control Unit (ECU): Downstream SCR catalyst temperature is too low.

The temperature reading from the exhaust gas temperature sensor located downstream of the Selective Catalytic Reduction (SCR) catalyst is falling below the minimum expected operating threshold. This may cause the ECU to halt DEF dosing and induce an engine derate or power loss.

• Tier 4b
• 240 Series Axial-Flow Combines (7240, 8240, 9240)
• Magnum series tractors
• Steiger series tractors
• Patriot Sprayers (4430)
• Compact Track Loaders and Skid Steers (TR340)

1. 1

   Check for related active faults, such as DTC 372C (SPN 14124) or other exhaust temperature/NOx sensor faults, and resolve them first.

2. 2

   Inspect the downstream SCR temperature sensor for proper physical installation; a loose sensor will read ambient outside air instead of exhaust gas.

3. 3

   Inspect the sensor's wiring harness and connector for chafing, melting from exhaust heat, corrosion, or backed-out pins.

4. 4

   Check the exhaust piping between the engine and the downstream SCR catalyst for severe leaks that allow heat to escape before reaching the sensor.

1. 1

   Cool Down

   Park the machine on a level surface, turn off the engine, and allow the exhaust aftertreatment system to cool completely. Exhaust components reach extreme temperatures and pose a severe burn risk.

2. 2

   Locate the Sensor

   Locate the downstream SCR temperature sensor. It is threaded into the exhaust pipe immediately after the SCR catalyst/muffler assembly.

3. 3

   Disconnect Wiring

   Unplug the electrical connector linking the sensor to the main engine wiring harness.

4. 4

   Remove the Sensor

   Using an appropriate wrench or sensor socket, carefully unscrew the sensor from the exhaust bung. Note: Penetrating oil may be required if the sensor threads are seized from heat cycling.

5. 5

   Prepare the New Sensor

   Apply a small amount of high-temperature anti-seize compound to the threads of the new sensor (if it does not come pre-applied). Do not get any anti-seize on the sensor probe itself, as this will contaminate the reading.

6. 6

   Install

   Thread the new sensor into the exhaust bung by hand to prevent cross-threading, then tighten to the OEM specified torque.

7. 7

   Reconnect

   Route the sensor wire safely away from direct heat sources and reconnect the electrical plug until it clicks.

8. 8

   Clear and Test

   Use the CNH Electronic Service Tool (EST) to clear the inactive 19068 fault code. Start the engine and run it under load to bring the exhaust up to operating temperature, verifying that the SCR system enters closed-loop DEF dosing and the code does not return.