Case IH 3766 – Engine ECU: Diesel Particulate Filter (DPF) Pressure Sensor: Fault check for the pressure sensor plausibility

The Engine Control Unit is receiving an implausible signal from the DPF differential pressure sensor. The sensor's voltage output does not align with the engine's current operating parameters, suggesting a failed sensor, a blocked/leaking pressure hose, or a wiring issue.

• Farmall
• skid steer
• SV250
• TR270
• TR320
• TV380
• Farmall 75C
• Farmall 90A
• Farmall 100A
• Farmall 115U
• Maxxum
• Puma
• Steiger
• 580SN

1. 1

   Check for related codes such as 3796, 3797, or 3798

2. 2

   Visually inspect the two hoses running from the exhaust pipe to the DPF differential pressure sensor for cracks, melting, disconnections, or soot/carbon blockages

3. 3

   Inspect the 3-pin connector at the DPF pressure sensor for corrosion, pushed-out pins, or moisture, and verify it receives the correct 5V reference voltage and ground from the Engine ECU

4. 4

   Use the EST to monitor DPF differential pressure live data with the engine off (should read 0) and running; a high pressure reading with the engine off indicates an internally shorted or stuck sensor

1. 1

   Turn off the machine and disconnect the negative battery cable.

   Ensure the machine is powered down before beginning the repair.

2. 2

   Locate the DPF Differential Pressure Sensor.

   Typically mounted on a bracket near the DPF assembly or on the engine block, connected to the exhaust via two high-temperature hoses.

3. 3

   Disconnect the electrical harness from the sensor.

   Carefully unplug the 3-pin connector.

4. 4

   Remove the hose clamps and pull the exhaust pressure hoses off the sensor nipples.

   Note: If the hoses are brittle or clogged with hard carbon, replace them as well.

5. 5

   Unbolt the sensor from its mounting bracket and remove it.

   Remove the old sensor from the machine.

6. 6

   Install the new OEM sensor and secure it to the bracket.

   Mount the replacement sensor in the original location.

7. 7

   Reconnect the pressure hoses.

   Ensure the upstream and downstream hoses are connected to the correct ports (they are usually different sizes to prevent mixing them up). Secure with clamps.

8. 8

   Reconnect the electrical harness.

   Plug the 3-pin connector back into the new sensor.

9. 9

   Restore Self-Learning Parameters.

   According to CNH service instructions, after replacing the sensor, you must use the EST (Electronic Service Tool) to reset the DPF pressure sensor learned values/self-learning parameters in the Engine ECU.

10. 10

    Clear the fault codes and run the engine to verify the repair.

    Ensure no codes return and the sensor reads correctly.