Case IH 19817 (DTC 377A) - ECU – DCU (Dosing Control Unit) or Engine Control Module (ECM / EEM): DEF/AdBlue dosing valve is blocked

The system has detected that the DEF (Diesel Exhaust Fluid) dosing valve (injector) is physically blocked or stuck in the closed position. Because the valve cannot open, the system is unable to inject DEF into the exhaust stream, which prevents the Selective Catalytic Reduction (SCR) system from converting harmful NOx emissions. If ignored, this will trigger an engine power derate.

• MAXXUM T4E
• 240 Series Axial-Flow Combines (7240, 8240, 9240)
• Steiger Series (350 to 600 HP)
• Magnum Series (235-340)
• Maxxum series tractors
• Puma series tractors
• T6 series tractors

1. 1

   Check DEF tank level to ensure it is not empty, as running dry prevents dosing and causes overheating.

2. 2

   Disconnect DEF lines and inspect for crystallized DEF fluid, which can mimic a blocked valve.

3. 3

   Check the DEF filter for severe clogs that could restrict fluid pressure to the dosing valve.

4. 4

   Run an electronic test using the Case IH Electronic Service Tool (EST) to verify if the valve is mechanically stuck or has an electrical issue.

5. 5

   Check the outlet exhaust gas temperature sensor, as a defective sensor can cause the system to halt dosing.

1. 1

   Depressurize system

   Allow the machine to sit with the key off for at least 5-10 minutes before servicing the DEF system so the DCU can complete its purge cycle and depressurize the lines.

2. 2

   Locate module

   Locate the DEF/AdBlue dosing module on the exhaust SCR catalyst unit.

3. 3

   Clean area

   Thoroughly clean the area around the dosing valve to prevent dirt from entering the SCR system.

4. 4

   Disconnect harness

   Disconnect the electrical harness connector from the dosing valve.

5. 5

   Disconnect and inspect lines

   Disconnect the DEF/AdBlue fluid lines from the dosing module. Inspect the line tips for heavy crystallization. (If crystallized, clean with warm distilled water).

6. 6

   Remove valve

   Remove the mounting bolts/clamp securing the dosing valve to the exhaust pipe/SCR housing and remove the blocked valve.

7. 7

   Install new valve

   Install the new DEF dosing valve and torque the mounting hardware to OEM specifications.

8. 8

   Reconnect components

   Reconnect the DEF fluid lines and the electrical harness.

9. 9

   Replace filter

   Replace the main DEF filter at this time to ensure clean fluid reaches the new valve.

10. 10

    Clear codes and test

    Connect a diagnostic tool to clear the 19817 / 377A fault code. Run a forced regeneration or a manual dosing test to prime the system and verify the repair.