Case IH 3775 (F-3251-15) - ECU – ECU: Particulate filter differential pressure value is higher than expected (filter full and requires parked catalyst management).

The engine control system has detected an excessive pressure drop across the Diesel Particulate Filter (DPF). The differential pressure sensor measures the exhaust pressure before and after the DPF; a reading higher than the programmed threshold indicates that the filter is severely restricted by soot or ash buildup and requires an immediate stationary (parked) regeneration to burn it off.

• VESTRUM CVX
• Farmall
• Puma
• Magnum
• Steiger

1. 1

   Review operating conditions to see if the tractor has been operating under light loads, excessive idling, or short duty cycles, which prevent automatic passive regenerations.

2. 2

   Inspect the physical hoses and tubes running from the DPF housing to the DPF differential pressure sensor for blockages (soot or ice buildup), cracks, melting, or disconnected lines.

3. 3

   Test the DPF differential pressure sensor and its wiring harness for chafing or damage. If the sensor reads a high pressure differential when the engine is off or at idle, the sensor itself is likely faulty.

4. 4

   Check the exhaust temperature sensors to ensure they are functioning correctly, as a faulty temperature sensor can prevent the ECU from allowing an active regeneration to start.

1. 1

   Perform a Parked Regeneration

   Move the machine to a safe, well-ventilated area away from combustible materials. Use the tractor's cab display monitor or an electronic diagnostic service tool to manually initiate a 'parked' (stationary) regeneration.

2. 2

   Monitor the Cycle

   Allow the engine to run through the complete regeneration cycle, which typically takes 30 to 45 minutes. Do not interrupt the process unless there is a safety hazard.

3. 3

   Clear and Retest

   Once the regeneration completes, clear the fault codes from the ECU. Run the engine under a working load to see if code 3775 returns.

4. 4

   Replace the Sensor

   If the parked regeneration fails to initiate, or if the code returns immediately despite the lines being clear, replace the DPF differential pressure sensor.

5. 5

   DPF Cleaning/Replacement

   If a new sensor does not resolve the issue and the filter remains restricted, the DPF is likely 'face-plugged' with incombustible ash (which regeneration cannot burn off). The DPF must be removed and sent to a specialized facility for professional pneumatic/thermal cleaning, or replaced entirely.