Case IH 3621 – Engine Control Unit (ECU): Urea quality and urea warning level 5

A consequential inducement or warning level code indicating a fault within the Selective Catalytic Reduction (SCR) / Diesel Exhaust Fluid (DEF) system, triggered by another leading active fault in the emissions system.

• Steiger Tractors 350, 400, 450, 500, 550, 600
• Quadtrac Tractors 450, 500, 550, 600
• Rowtrac Tractors 350, 400, 450, 500
• Puma Series Tractors
• Axial-Flow Combines (e.g., 240 Series)
• Maxxum Series Tractors

1. 1

   Connect the Case IH Electronic Service Tool (EST) to the machine's diagnostic port.

2. 2

   Pull all active and stored fault codes from the Engine Control Unit (ECU).

3. 3

   Look for the primary leading fault code related to the SCR/DEF system (e.g., codes relating to the NOx sensors, DEF dosing valve, DEF pressure, or DEF quality sensors).

4. 4

   Check the physical condition of the DEF fluid to ensure it is not contaminated or degraded.

1. 1

   Identify the Root Cause

   Ignore code 3621 temporarily and focus on the other active SCR-related fault codes found during your diagnostic check.

2. 2

   Perform Primary Repair

   Troubleshoot and replace the component dictated by the primary fault code (e.g., replacing a failed NOx sensor, draining and replacing bad DEF fluid, or replacing a clogged DEF filter).

3. 3

   Clear Codes

   Once the primary mechanical or electrical repair is completed, use the EST to erase all faults listed in the ECU.

4. 4

   Validation Drive/Run

   Bring the engine up to operating temperature and run it under load. The SCR system must complete a cycle to verify that emissions are within acceptable limits and to ensure the warning level 5 inducement does not return.