Case IH 19559 (F-1761-17) – Engine Control Unit (ECU) or Aftertreatment Control Module: DEF/AdBlue level too low warning is active - Stage 1

This code indicates that the Diesel Exhaust Fluid (DEF) / AdBlue level in the tank has dropped below the first warning threshold (Stage 1). It is an operational warning rather than a component failure, though a faulty sensor can falsely trigger it.

• VESTRUM CVX
• 240 Series Axial-Flow Combines
• AUSTOFT 9900 Sugarcane Harvesters
• Steiger Tractors
• Magnum Tractors
• Farmall Tractors

1. 1

   Visually inspect the DEF/AdBlue tank to confirm if the fluid level is actually low.

2. 2

   Inspect the DEF tank, supply lines, and dosing module for any physical leaks that could cause rapid fluid loss.

3. 3

   Verify if there are other active codes related to the DEF level sensor circuit (e.g., DTC 19650 or 19651) which indicate an electrical issue rather than just low fluid.

4. 4

   Use a diagnostic scan tool to read live data from the DEF level sensor and compare the reported percentage to the actual physical fluid level in the tank.

1. 1

   Refill the Tank

   Fill the DEF/AdBlue tank with fresh, uncontaminated Diesel Exhaust Fluid.

2. 2

   Cycle the Key

   Turn the ignition on and allow the system to initialize so the ECU can read the new fluid level.

3. 3

   Clear Codes

   If the warning does not clear automatically after refilling, use a diagnostic tool to clear the inactive fault code.

4. 4

   Inspect Wiring

   If the tank is full but the code remains active, inspect the wiring harness and connector at the DEF tank header unit for corrosion, bent pins, or chafing.

5. 5

   Replace the Sensor

   If the wiring is intact but the sensor still reports a low/empty tank when full, the DEF level sensor (often integrated into the DEF header unit) has failed and must be replaced.