Case IH 3869 – Engine Control Unit (ECU): SCR2 message: low urea level

The system has detected that the Diesel Exhaust Fluid (DEF / Urea) in the tank has dropped below the minimum required operating threshold.

• Steiger
• Magnum
• Farmall
• Austoft sugarcane harvesters

1. 1

   Physically check the DEF/urea tank to confirm if it is actually empty or low

2. 2

   Determine if the ECU is logging other DEF sensor codes alongside 3869 (e.g., 3A8, 4A8, P203C, P203D)

3. 3

   Inspect the wiring harness and connector at the DEF tank header/sensor for corrosion, damage, or loose connections

1. 1

   Refill the Tank

   Fill the DEF tank with clean, correct-specification Diesel Exhaust Fluid.

2. 2

   Clear and Retest

   Cycle the key, clear the fault codes using an Electronic Service Tool (if necessary), and run the engine to see if the code clears.

3. 3

   Test the Sensor

   If the tank is full but the ECU still registers a low level, use a multimeter to test the DEF level sensor for proper voltage and continuity.

4. 4

   Replace the Sensor

   If the wiring harness is intact but the sensor fails to send the correct level signal to the ECU, the DEF level sensor (often integrated into the DEF header unit) has failed internally and must be replaced.