Case IH 19289 – DCU (Dosing Control Unit): Temperature after catalyst too low | Downstream catalyst temp - physical (Catalyst heating time failed) | P042B Catalyst Temperature Sensor Circuit Range/Performance

The Selective Catalytic Reduction (SCR) system is not detecting the expected temperature rise at the outlet of the neutralizer/catalyst within the required timeframe. The system suspects a range or performance issue with the downstream catalyst temperature sensor.

• Tier 4a
• Case IH Magnum Series (235, 260, 290, 315, 340, 370 - Series 4)
• Case IH Steiger / STX Series (350 to 600 horsepower)
• Case IH Puma Series
• Case IH Farmall Series
• Case IH 240 Series Combines
• Case IH Tier 4B Construction Equipment (e.g., 580N EP Backhoe Loaders)

1. 1

   Check if the downstream temperature sensor is physically installed correctly and has not backed out or become loose in the exhaust tube

2. 2

   Drive the vehicle under a heavy working load to generate sufficient exhaust heat and monitor live data to see if the temperature after the catalyst reaches the required threshold

3. 3

   Ensure the DEF tank is not empty, as a low UREA level can cause air suction in the lines, disrupting the dosing and heating process

4. 4

   Inspect the wiring harness and connectors leading to the downstream catalyst temperature sensor for chafing, corrosion, or open/short circuits

5. 5

   Verify that the machine's data set has not been tampered with (e.g., unauthorized emissions tuning or 'deletes')

1. 1

   Secure the Sensor

   If the diagnostic inspection reveals the sensor is loose, clean the threads, reinstall it securely into the downstream exhaust tube, and re-test the machine under load.

2. 2

   Replace the Sensor

   If the wiring is intact, the DEF fluid level is adequate, and the machine still fails to reach the downstream temperature threshold under heavy load, the downstream catalyst temperature sensor has internally failed and must be replaced.

3. 3

   Install New Sensor

   Disconnect the negative battery terminal. Unplug the sensor connector, remove the faulty sensor from the exhaust piping, apply high-temp anti-seize to the threads of the new sensor (if not pre-applied), and install the new sensor.

4. 4

   Clear Codes and Test

   Reconnect the battery, use a diagnostic scan tool to clear the 19289 / P042B code from the DCU, and perform a forced stationary regeneration or a heavy-load test drive to verify the SCR system reaches operating temperature and the code does not return.