New Holland 19164 – DCU: Reductant Purge Control Valve Open Circuit

The Dosing Control Unit (DCU) has detected an open circuit in the electrical path for the Reductant Purge Control Valve (also referred to as the Vent Valve). This indicates a break or disconnection in the wiring, a faulty connector, or an internal failure within the valve's solenoid coil, preventing electrical current from flowing. This valve is critical for managing Diesel Exhaust Fluid (DEF) flow, specifically during machine shutdown when it reverses the pump to purge DEF from the lines to prevent freezing or crystallization.

• T6
• T7
• T8
• CR Series Combines
• Loaders

1. 1

   Perform a visual inspection of the wiring harness leading to the Reductant Purge Control Valve for chafing, rubbing, melting, or rodent damage.

2. 2

   Disconnect the electrical connector at the valve and inspect terminals on both the harness and valve sides for corrosion, moisture, or pushed-out/damaged pins.

3. 3

   Check any fuses related to the SCR or engine control system to ensure power is not being interrupted by a blown fuse.

4. 4

   Test wiring continuity between the DCU connector and the valve connector using a multimeter (a reading of near zero ohms indicates a good wire).

5. 5

   Measure the resistance across the two terminals on the valve itself (typically 20-40 ohms). An 'OL' (Open Line) or infinite reading indicates an internal open circuit within the valve's coil.

1. 1

   Safety First

   Park the machine on a level surface, turn off the engine, and engage the parking brake. Allow the machine and exhaust components to cool down.

2. 2

   Locate the Valve

   The Reductant Purge Control Valve is part of the SCR system, typically located on the DEF pump or in the lines between the pump and the injector. Its exact location can vary by machine model.

3. 3

   Perform Diagnostic Checks

   Follow the diagnostic steps outlined above to determine the root cause (wiring, connector, or valve).

4. 4

   Repair Wiring or Connectors

   If a wiring issue is found, repair the damaged section with appropriate connectors and seal it from moisture. If a connector is corroded or damaged, it should be cleaned or replaced.

5. 5

   Replace the Reductant Purge Control Valve

   If the diagnostic tests confirm the valve itself is faulty (i.e., has an open internal coil), it must be replaced. Disconnect the electrical connector. Carefully disconnect the DEF lines attached to the valve. Be prepared for potential DEF spillage and wear appropriate personal protective equipment. Remove the bolts or clips securing the valve and remove it from the machine. Install the new valve, ensuring all connections are secure. Reconnect the DEF lines and the electrical connector.

6. 6

   Clear Fault Codes

   After the repair is complete, use a diagnostic tool to clear the 19164 fault code from the DCU.

7. 7

   Verify the Repair

   Start the machine and allow the SCR system to run a self-test. Monitor for the return of the fault code to ensure the repair was successful.