Case IH 3931 – Engine Control Unit (ECU): Info: SCR Inducement: Warning Block 4 activated

This is a secondary, informational fault code indicating that the engine's Selective Catalytic Reduction (SCR) system has initiated an inducement strategy (such as a progressive engine torque derate or severe operator warning) due to another leading active fault within the emissions system.

• Case IH and New Holland agricultural equipment (tractors, combines, sprayers) equipped with Tier 4a and Tier 4b FPT engines

1. 1

   Connect the CNH Electronic Service Tool (EST) and pull all active and stored fault codes to identify the primary leading fault code

2. 2

   Inspect the wiring and connectors to the ECU and DCU, verifying they are undamaged, properly seated, and locks are not broken

3. 3

   Use the EST to verify healthy communication across the CAN network between the ECU and DCU

4. 4

   Ensure the Diesel Exhaust Fluid (DEF) tank is full, the fluid is not expired or contaminated, and there are no obvious leaks in the DEF supply lines

1. 1

   Identify the Primary Fault

   Review the list of active codes. Ignore 3931 for the moment and focus entirely on the other active SCR/Emissions codes.

2. 2

   Perform Primary Troubleshooting

   Follow the specific diagnostic procedure for the primary code. For example, if a NOx sensor code (like E1726-03) is present, check that the sensor is receiving 24V power and a sufficient ground.

3. 3

   Repair the Root Cause

   Repair damaged wiring or replace the failed component (e.g., NOx sensor, DEF pump, DEF injector) dictating the primary fault.

4. 4

   Clear Codes

   Once the primary repair is complete, use the EST to clear the fault codes.

5. 5

   Validation Run

   Run the machine under load. If the primary fault was successfully repaired, the ECU will recognize that the emissions system is functioning properly, and the '3931 SCR Inducement: Warning Block 4' code will automatically deactivate.