New Holland ENG 3997 – ENGINE: Delta P Sensor: Vod is Out of Voltage - High

The Engine Control Unit (ECU) is receiving a signal voltage from the Delta P (ΔP) Sensor that exceeds the maximum expected operating threshold. This is an electrical circuit fault, typically caused by a short to power on the sensor signal wire, an open ground circuit, or an internal short or failure within the sensor itself.

• L220
• SR175
• L175
• C232
• C238
• B90B
• B100B
• FR480

1. 1

   Visual Inspection: Locate the Delta P sensor (typically mounted on a bracket near the DPF/DOC or SCR exhaust components). Inspect the sensor, its electrical connector, and the wiring harness for physical damage, melted wires, corrosion, or loose pins.

2. 2

   Ground Circuit Test: Using a multimeter, test the sensor's ground circuit for continuity. An open ground is a primary cause for a Voltage High code.

3. 3

   Signal Circuit Test: Check the signal wire for a short to a voltage source.

4. 4

   Reference Voltage Test: Verify that the 5V reference supply to the sensor is within specification and not shorting to the signal wire.

5. 5

   Hose/Tube Inspection: Inspect the two pressure hoses/tubes connecting the sensor to the exhaust system. While physical blockages usually trigger pressure-related codes, melted or severely damaged tubes can sometimes cause secondary heat damage to the sensor, leading to internal electrical shorts.

1. 1

   Turn off the engine, remove the key, and disconnect the battery to ensure electrical safety.

2. 2

   Locate the Delta P sensor on its mounting bracket near the exhaust aftertreatment unit.

3. 3

   Depress the locking tab and disconnect the electrical wiring harness connector from the sensor.

4. 4

   Carefully disconnect the two pressure hoses/tubes from the bottom of the sensor.

   Note their orientation, as reversing the high and low pressure lines during reassembly will cause immediate fault codes.

5. 5

   Remove the mounting hardware (screws/bolts) securing the sensor to its bracket.

6. 6

   Install the replacement Delta P sensor onto the bracket and secure the hardware.

7. 7

   Reconnect the pressure hoses to the correct ports on the new sensor.

8. 8

   Reconnect the electrical harness connector until it clicks securely into place.

9. 9

   Reconnect the battery and turn the ignition on.

10. 10

    Use a diagnostic scan tool to clear the ENG 3997 fault code from the Engine ECU.

11. 11

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