Case IH 19817 – Engine Control Unit (ECU) / Dosing Control Unit (DCU): Plausibility of UDV (Urea Dosing Valve) stuck - Reagent dosing valve - blocked (only stuck closed)

The NOx neutralization node (DEF power module) has detected that the DEF/AdBlue fluid pressure has exceeded 6.5 bar (650 kPa) for 30 seconds. This overpressure condition indicates that the dosing valve is physically blocked or stuck in the closed position.

• Tier 4a
• Tier 4b
• Magnum 180
• Magnum 200
• Magnum 220
• Magnum 235
• Magnum 240
• Magnum 250
• Magnum 260
• Magnum 280
• Magnum 290
• Magnum 310
• Magnum 315
• Magnum 340
• Magnum 370
• Magnum 380
• Steiger 350
• Steiger 400
• Steiger 450
• Steiger 500
• Steiger 550
• Steiger 600
• Quadtrac 350
• Quadtrac 400
• Quadtrac 450
• Quadtrac 500
• Quadtrac 550
• Quadtrac 600
• Puma 140
• Puma 150
• Puma 165
• Puma 185
• Puma 200
• Puma 220
• Puma 240
• Maxxum Series
• Optum Series
• Farmall Series

1. 1

   Visual Inspection for Scale: Remove the dosing injector and inspect the tip and the exhaust mixing chamber. Look for white scale deposits (crystallized urea). If scale is present, it prevents the vaporized DEF/AdBlue from mixing properly and blocks the valve.

2. 2

   Fluid Quality Check: Verify the DEF/AdBlue concentration. It should measure exactly 32.5% automotive-grade urea to 67.5% distilled water. If the concentration is incorrect, the fluid must be drained and replaced.

3. 3

   Electronic Service Tool (EST) Testing: Connect the EST and run a Urea Dosing System Test (UDST) to monitor the DEF pump pressure and speed.

4. 4

   Parameter Verification: During the UDST, verify that the DEF/AdBlue pressure does not exceed 500 kPa (5 bar) and the pump speed does not exceed 6000 RPM. If these measurements are abnormally high and no physical blockage exists, the internal DEF power module/pump is faulty.

5. 5

   Wiring Check: Ensure the electrical connectors between the dosing valve, pressure sensors, and the ECU are tight, undamaged, and free of corrosion.

1. 1

   Power Down

   Turn off the machine and disconnect the battery to ensure the ECU is powered down.

2. 2

   Disconnect Electrical Harness

   Locate the Urea Dosing Valve (UDV) on the exhaust system and disconnect its electrical harness connector.

3. 3

   Disconnect DEF Lines

   Squeeze the locking tabs together on the DEF supply and return hoses and pull straight upward to disconnect them from the elbow. Cap all open fittings to prevent contamination.

4. 4

   Remove the Valve

   Unbolt and remove the dosing valve from the exhaust mixing chamber.

5. 5

   Clean or Replace

   If the mixing chamber is clogged with scale, clean it thoroughly. If the dosing valve is stuck closed or heavily scaled, replace it with a new unit.

6. 6

   Replace Supply Module (If necessary)

   If the valve was not blocked but the EST test showed pressure >500 kPa or speed >6000 RPM, replace the NOx neutralization node (DEF supply module).

7. 7

   Reassembly

   Install the new dosing valve, reconnect the DEF hoses (ensuring they click into place), and plug in the electrical harness.

8. 8

   Clear Codes and Test

   Use the EST to clear the DCU/ECU fault codes. The engine must be brought to operating temperature and run under load until the ECU determines the SCR system is operating properly and the code does not return.