Case IH 19081 – VCM, DCU, or Engine ECU (EDC): DEF/AdBlue dosing valve actuator short circuit to ground in high side failure

The control module has detected that the electrical circuit supplying voltage (the high side) to the Diesel Exhaust Fluid (DEF) dosing valve actuator has shorted to ground. This electrical failure prevents the valve from opening, meaning no DEF is injected into the exhaust stream, which will eventually lead to an SCR efficiency failure and an engine derate.

• Tier 4b
• 240 Series Axial-Flow Combines
• N-Series Tractor Loader Backhoes (TLBs)
• Magnum tractors
• Steiger tractors

1. 1

   Visually inspect the wiring harness connecting the DCU/VCM to the DEF dosing valve for chafed insulation, bare wires rubbing against the frame or exhaust components, or pinched wires.

2. 2

   Disconnect the electrical connector at the DEF dosing valve and use a multimeter to check for continuity to ground on the high-side supply wire of the harness.

3. 3

   Remove the dosing module and visually inspect the DOC (Diesel Oxidation Catalyst) exhaust gas mixing chamber and the DEF injector port for severe DEF crystallization (white buildup) that may have caused the valve to overheat or fail.

4. 4

   Verify if related codes, such as DTC 467A / 19174 (DEF/AdBlue dosing valve actuator short circuit in high side failure), are also active. Diagnose active short circuits first.

1. 1

   Disconnect power

   Turn off the machine, remove the key, and disconnect the battery to prevent electrical spikes.

2. 2

   Repair wiring harness

   If the multimeter test revealed a harness issue, trace the wire back to the DCU and repair or replace the damaged section of the wiring harness.

3. 3

   Replace DEF dosing valve

   If the wiring harness is intact, the DEF dosing valve itself has suffered an internal short and must be replaced.

4. 4

   Disconnect dosing valve

   Disconnect the electrical connector and the DEF fluid supply line from the dosing valve. (Be prepared to catch a small amount of spilled DEF).

5. 5

   Remove dosing valve

   Unbolt the DEF dosing valve from the exhaust mixing chamber.

6. 6

   Clean injector port

   Clean any crystallized DEF from the injector port on the exhaust using warm water and a soft brush. Do not let large chunks of crystal fall into the exhaust stream.

7. 7

   Install new dosing valve

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

8. 8

   Reconnect lines

   Reconnect the DEF fluid supply line and the electrical connector.

9. 9

   Restore power

   Reconnect the battery and turn the ignition on.

10. 10

    Clear fault code

    Use the CNH EASy diagnostic tool (or an equivalent heavy-duty scanner) to clear the fault code.

11. 11

    Verify repair

    Start the engine and perform a stationary regeneration or a forced DEF dosing test to verify the system is operating correctly and the code does not return. Note: Some replacement modules may require programming or calibration to the vehicle after replacement.