Case IH 3776 – Engine Control Unit (ECU) / EDC: Diesel particulate filter (DPF) : Monitoring of the characteristic pressure reduction of the particulate filter - min

The differential pressure (the difference in exhaust pressure measured before and after the DPF) has dropped below the minimum expected threshold. This typically means the exhaust is bypassing the filter or the sensor is failing to read the pressure correctly.

• Farmall series (e.g., 105C, 115U)
• Maxxum series (e.g., 110 EP, 140 EP)
• Puma series
• Magnum tractors
• Steiger tractors
• Combines (e.g., 2388 and newer emissions-compliant models)

1. 1

   Visual Inspection of Hoses: Locate the DPF differential pressure sensor. Inspect the two hoses running from the exhaust pipe/DPF to the sensor for cracks, heat damage, blockages (soot/ice), or hoses that have blown off their fittings.

2. 2

   Wiring and Connector Check: Inspect the 3-pin connector at the differential pressure sensor for corrosion, pushed-out pins, or chafed wires.

3. 3

   Live Data Monitoring: Using a diagnostic scan tool, monitor the DPF differential pressure sensor voltage/pressure output. With the key on and engine off, the pressure should read zero. If it reads a vacuum or a high pressure without the engine running, the sensor is skewed and faulty.

4. 4

   DPF Substrate Inspection: If the sensor and lines are perfectly intact and reading correctly, the DPF itself must be removed and inspected for internal cracking or a melted substrate that is allowing exhaust to pass through without restriction.

1. 1

   Safety First

   Ensure the tractor is parked on a level surface, the engine is turned off, the key is removed, and the exhaust system has completely cooled down to prevent severe burns.

2. 2

   Locate the Sensor

   Find the DPF differential pressure sensor, which is typically mounted on a bracket near the DPF housing to isolate it from extreme exhaust heat.

3. 3

   Replace Hoses (If Damaged)

   Loosen the clamps securing the hoses to the exhaust bungs and the sensor. Remove the old hoses. Clear the metal exhaust bungs of any hard soot buildup using a pick or wire. Install new high-temperature silicone/rubber hoses and secure them with clamps.

4. 4

   Replace the Sensor (If Faulty)

   Disconnect the electrical harness from the sensor. Remove the hoses from the bottom of the sensor (note which hose goes to the upstream port and which goes to the downstream port; they must not be reversed). Unbolt the sensor from its mounting bracket. Bolt the new OEM sensor into place, reattach the hoses in the correct orientation, and plug in the electrical connector.

5. 5

   Clear Codes and Reset

   Connect a diagnostic tool to the machine, clear the 3776 fault code, and perform a DPF pressure sensor calibration/reset if required by the specific engine software.

6. 6

   Test Run

   Start the engine and monitor live DPF pressure data to ensure it rises appropriately as engine RPM and load increase.