Case IH 19290 – DCU (Dosing Control Unit) or Engine ECU: Temperature after catalyst too low – Downstream catalyst temp - physical (Catalyst heating time failed) – P042B Catalyst Temperature Sensor - Circuit Range/Performance

The control module has detected that the exhaust temperature downstream of the catalyst is not reaching the required threshold within the expected timeframe. The system monitors the ratio between the upstream and downstream temperature sensors, and this code triggers when that ratio falls below the acceptable limit, indicating either a physical exhaust issue or a faulty downstream temperature sensor.

• Tier 4a
• Tier 4b
• Case IH Magnum Tractors (235 - 340, Series 4)
• Case STX Steiger Tractors (350 - 600)
• Case IH Puma Tractors (125, 140, 210, etc.)
• Case IH Maxxum Tractors (120, 125, 130, 140)
• Case IH Farmall Tractors (100C, 105A/C/U, 110A/C/U, 115A/C/U, 120U)
• Case Construction Equipment (e.g., 580N EP Backhoe Loader, 721F, 821F, 921F Wheel Loaders)

1. 1

   Verify that both the upstream and downstream exhaust gas temperature sensors are installed correctly and securely

2. 2

   Inspect the muffler and Diesel Oxidation Catalyst (DOC) for any physical damage

3. 3

   Inspect exhaust piping to ensure it is mounted correctly and has no leaks that could allow heat to escape before reaching the downstream sensor

4. 4

   Use the Electronic Service Tool (EST) to monitor live temperature readings of the upstream and downstream sensors to confirm if the downstream sensor is reading out of range or dead

1. 1

   Turn off the machine and allow the exhaust system to cool completely to avoid burns.

2. 2

   Perform the visual inspection of the exhaust piping, muffler, and sensor mounting as outlined in the diagnostic checks.

   Fix any exhaust leaks if found.

3. 3

   Locate the downstream catalyst temperature sensor (Exhaust Gas Temperature Sensor) on the exhaust pipe after the catalyst.

4. 4

   Inspect the sensor's wiring harness and connector (typically a 2-pin Bosch connector) for melting, corrosion, or wire chafing.

5. 5

   Disconnect the sensor from the wiring harness.

   If the wiring is intact and no exhaust leaks are present, the sensor itself has likely failed.

6. 6

   Remove the faulty sensor from the exhaust pipe (standard M14x1.5 thread).

7. 7

   Install the new OEM Exhaust Gas Temperature Sensor.

8. 8

   Reconnect the wiring harness.

9. 9

   Clear the fault codes using the Case IH Electronic Service Tool (EST) or equivalent diagnostic scanner.

10. 10

    Run the machine through a standard operating cycle or forced regeneration to verify the catalyst reaches the proper heating temperature and the code does not return.