New Holland ENG 3798 – ENGINE: Diesel Particulate Filter (DPF) Pressure Sensor: SRC low for Particulate Filter Differential Pressure Sensor

This code indicates that the voltage signal from the DPF differential pressure sensor has dropped below the minimum acceptable threshold. A 'Signal too Low' condition typically points to an electrical issue (short to ground or open circuit), a disconnected/ruptured sensor hose, or a failed sensor.

• T4 series
• T4.115
• T5 series
• T6 series
• Workmaster
• Boomer series
• L220
• L223
• L225
• L230
• C232
• C238

1. 1

   Visually inspect the two small metal/rubber hoses (differential pressure pipes) connecting the DPF housing to the pressure sensor for cracks, melting, blockages, or disconnection.

2. 2

   Inspect the sensor's electrical connector and the wiring harness routing back to the ECU for chafed wires, corrosion in the pins, or a short to ground.

3. 3

   Using a multimeter, verify that the sensor is receiving the correct 5V reference voltage from the ECU. Check the signal wire to see if the voltage is stuck below the normal operating range (below 0.5V).

4. 4

   Check DPF integrity for a physically cracked or hollowed-out substrate, which can result in zero pressure differential and trigger plausibility faults.

1. 1

   Power Down

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

2. 2

   Locate the Sensor

   Locate the DPF differential pressure sensor. It is typically mounted on a bracket near the DPF assembly (DOC/DPF exhaust tube) and has two hoses and a 3-pin electrical connector attached to it.

3. 3

   Repair Hoses/Wiring

   If the diagnostic checks revealed a burnt hose or a broken wire, repair the harness or replace the differential pressure pipes.

4. 4

   Replace the Sensor

   If the wiring and hoses are intact, the sensor itself has failed internally. Disconnect the electrical connector. Release the hose clamps and pull the two pressure hoses off the sensor nipples (note which hose goes to the upstream vs. downstream port). Unbolt the sensor from its mounting bracket and install the new OEM sensor. Reconnect the hoses, secure the clamps, and plug in the electrical connector.

5. 5

   Clear Codes and Verify

   Reconnect the battery. Use an Electronic Service Tool (EST) to clear the active ENG 3798 fault code.

6. 6

   Test Run

   Start the engine and let it reach operating temperature. You may need to perform a stationary/forced DPF regeneration to ensure the new sensor is reading the pressure differential correctly and that the code does not return.