Case IH 19786 – Engine Control Unit (ECU): SCR Inducement: Warning, triggered by Customer Moderate fault or DEF/AdBlue dosing interruption fault

The Selective Catalytic Reduction (SCR) system has detected an interruption or failure in the Diesel Exhaust Fluid (DEF/AdBlue) dosing system. When this code is triggered, the machine will typically enter a power-reduction or limp mode (derate) to comply with emissions regulations.

• Tier 4b
• Puma 160
• Puma 185
• Magnum 225
• Magnum 290
• Steiger 450
• Farmall 90C
• Farmall 95A
• Farmall 115U
• Farmall 120C
• Optum
• Maxxum
• Vestrum
• Axial-Flow 5130
• Axial-Flow 6130
• Axial-Flow 7130
• Axial-Flow 7230
• Axial-Flow 8240
• Axial-Flow 9240
• Case TR340
• Case SV300
• Case TV380
• N-Series Loaders

1. 1

   Check DEF fluid quality and level to ensure sufficient fluid and purity (32.5% high-purity urea and 67.5% deionized water), looking for contamination (dirt, diesel, coolant) or dilution.

2. 2

   Visually inspect the DEF tank, lines, and injector nozzle for white, crystallized urea deposits that block fluid flow.

3. 3

   Perform a pressure buildup test to ensure the system pressurizes the DEF lines (checking for dried pump membranes or air leaks).

4. 4

   Verify NOx and Exhaust Gas Temperature (EGT) sensors, as faulty sensors reporting incorrect values can falsely trigger a dosing interruption.

5. 5

   Inspect DEF lines for cracks, leaks, or winter freeze damage.

1. 1

   Drain and Flush

   If the DEF is contaminated, old, or crystallized, completely drain the DEF tank and flush the system.

2. 2

   Clean/Replace Filters

   Remove and replace the main DEF filter. Clean any inline screens.

3. 3

   Clean the Injector

   Remove the DEF injector (dosing valve) from the exhaust stream and clean off any crystallized buildup. If it is mechanically failed or shorted, replace it.

4. 4

   Address the Pump

   If the system still cannot build pressure after cleaning and refilling with fresh DEF, the DNOX supply module (DEF pump) has likely failed internally and must be replaced.

5. 5

   Refill

   Refill the tank with fresh, certified ISO-standard DEF.

6. 6

   Software Reset & Regen

   Connect the Case IH Electronic Service Tool (EST) laptop to reset the SCR ECU data, clear the codes, and perform a forced regeneration or run the tractor under a heavy load (high exhaust temps) to burn the catalyst clean.