Case IH 3589 – Engine ECU and DNox Control Unit: Plausibility check of catalyst system - Temperature Deviation between up- and downstream Catalyst Temperature too high during Operation.

This code indicates a failure within the Selective Catalytic Reduction (SCR) system. The Engine Control Unit has detected that the temperature difference between the two Exhaust Gas Temperature (EGT) sensors (upstream and downstream of the SCR catalyst) is too great, triggering an SCR system failure warning and forcing the machine into limp home mode.

• Magnum
• Puma
• Steiger
• Quadtrac
• Maxxum
• Optum
• Farmall
• SR series
• TR series
• F series
• G series

1. 1

   Connect the Case IH Electronic Service Tool (EST) laptop to monitor live data for both the upstream and downstream EGT sensors to determine which sensor is reading erratically, dropping out, or stuck out of range.

2. 2

   Inspect the wiring harnesses and connectors leading to the EGT sensors on the SCR muffler for melting, chafing, or corrosion.

3. 3

   Look for other hidden codes in the ECU that might point to a specific sensor circuit failure (e.g., open load or short circuit).

1. 1

   Replace the Faulty Sensor

   Once the faulty EGT sensor (upstream or downstream) is identified via the EST laptop, remove and replace it.

2. 2

   Reset the SCR System

   Use the EST laptop to manually reset the SCR system and clear the fault codes to exit limp home mode.

3. 3

   Software Update

   Check the software versions on both the Engine ECU and the DNox unit, and flash/update both controllers to the newest software version to prevent overly sensitive plausibility logic from triggering the code again.