New Holland ENG 3996 – ISM-IDI Engine ECU: Delta P Sensor: Vod is Out of Voltage - Low

The Engine Control Unit is receiving a voltage signal from the Delta P sensor that has dropped below the minimum acceptable threshold. This typically indicates a short to ground in the sensor's wiring circuit, a disconnected harness, or an internal failure of the sensor itself.

• L175
• L220
• SR175
• SV series
• C232
• C238
• TR/TV series
• FR480

1. 1

   Check the electrical connector at the Delta P sensor for corrosion, backed-out pins, or moisture.

2. 2

   Inspect the wiring harness between the sensor and the Engine ECU for chafing, open circuits, or a short to ground.

3. 3

   Verify with a multimeter that the sensor is receiving the correct 5V reference voltage from the ECU and has a solid ground connection.

4. 4

   Inspect the physical hoses and metal tubes connecting the Delta P sensor to the exhaust/DPF for blockages (ports plugged with soot), melting, cracking, or leaks.

5. 5

   Ensure the DPF itself is not severely clogged, which can cause abnormal pressure readings.

1. 1

   Turn off the engine, remove the key, and disconnect the battery to prevent electrical shorts.

   Turn off the engine, remove the key, and disconnect the battery to prevent electrical shorts.

2. 2

   Locate the Delta P sensor, which is typically mounted on a bracket near the DPF or exhaust system.

   Locate the Delta P sensor, which is typically mounted on a bracket near the DPF or exhaust system.

3. 3

   Disconnect the electrical harness connector from the sensor.

   Disconnect the electrical harness connector from the sensor.

4. 4

   Carefully loosen the clamps or unions and disconnect the two pressure hoses/tubes from the sensor.

   Carefully loosen the clamps or unions and disconnect the two pressure hoses/tubes from the sensor. Note their orientation so they are not reversed during reinstallation.

5. 5

   Unbolt the sensor from its mounting bracket and remove it.

   Unbolt the sensor from its mounting bracket and remove it.

6. 6

   Install the new Delta P sensor onto the bracket.

   Install the new Delta P sensor onto the bracket.

7. 7

   Reconnect the pressure hoses, ensuring the clamps/unions are tight to prevent exhaust leaks.

   Reconnect the pressure hoses, ensuring the clamps/unions are tight to prevent exhaust leaks.

8. 8

   Plug in the electrical harness connector.

   Plug in the electrical harness connector.

9. 9

   Reconnect the battery, turn on the machine, and use a diagnostic service tool to clear the ENG 3996 fault code.

   Reconnect the battery, turn on the machine, and use a diagnostic service tool to clear the ENG 3996 fault code.

10. 10

    Run the engine and, if necessary, perform a stationary DPF regeneration to verify the sensor is reading differential pressure correctly and the code does not return.

    Run the engine and, if necessary, perform a stationary DPF regeneration to verify the sensor is reading differential pressure correctly and the code does not return.