New Holland NH 3109 – Engine Control Unit (ECU): CC HS Power stage 1 fuel press. Control - NO SIGNAL

The engine controller has detected an open circuit or a complete loss of communication ("NO SIGNAL") on the High Side Current Control ("CC HS") circuit for the fuel pressure control valve.

• T6 series
• T7 series
• T7000 series

1. 1

   Visually inspect the fuel pressure control valve electrical connector for disconnected plugs, pushed-out pins, moisture, or severe corrosion.

2. 2

   Test wiring harness continuity from the fuel pressure control valve back to the Engine ECU to ensure there are no broken, chafed, or melted wires causing an open circuit.

3. 3

   Measure the resistance across the pins of the fuel pressure control valve solenoid. An open circuit (infinite resistance) indicates the valve's internal coil has failed.

4. 4

   Inspect the Engine ECU connectors for any bent pins or water ingress that could interrupt the signal.

1. 1

   Safety First

   Turn off the machine, remove the key, and disconnect the negative battery terminal to prevent electrical shorts.

2. 2

   Access the Pump

   Locate the Bosch CP3 high-pressure fuel pump on the engine block. The fuel pressure control valve (M-PROP) is mounted directly to it.

3. 3

   Clean the Area

   Thoroughly clean the area around the valve to prevent dirt from entering the high-pressure fuel system during removal.

4. 4

   Disconnect and Remove

   Unplug the electrical connector. Remove the mounting screws holding the control valve to the pump housing.

5. 5

   Install the New Valve

   Lubricate the O-rings on the new fuel pressure control valve with clean diesel fuel. Carefully insert the new valve into the pump housing and tighten the mounting screws to the manufacturer's torque specification.

6. 6

   Reassemble

   Reconnect the electrical harness, ensuring the plug clicks securely into place. Reconnect the battery.

7. 7

   Clear Codes and Test

   Use a diagnostic tool or DTC eraser to clear the NH 3109 fault code from the Engine ECU. Start the engine, check for fuel leaks, and verify that the engine runs smoothly without derating or triggering the code again.