Case IH 3775 – Engine Control Unit (ECU) / EDC (Electronic Diesel Control): Diesel particulate filter (DPF) : Monitoring of the characteristic pressure reduction of the particulate filter - max

The differential pressure (pressure drop) across the Diesel Particulate Filter has reached its maximum allowable limit. This indicates the DPF is severely restricted or clogged due to excessive soot or ash accumulation, or there is a physical malfunction with the differential pressure sensor or its connecting hoses.

• Farmall 105C
• Farmall 115U
• Maxxum 100
• Maxxum 110
• Maxxum 115
• Maxxum 125
• Maxxum 130
• Maxxum 140
• Puma
• Magnum
• Steiger

1. 1

   Inspect the two hoses/lines connecting the DPF to the differential pressure sensor for cracks, melting, blockages (carbon buildup), or loose connections.

2. 2

   Check the wiring harness and the 3-pin connector at the differential pressure sensor for corrosion, chafing, or broken wires.

3. 3

   Connect the CNH Electronic Service Tool (EST) / EASY diagnostic tool and monitor live differential pressure sensor readings. With the engine off, pressure should read at or near zero.

4. 4

   Use the diagnostic tool to check the calculated soot and ash load levels in the ECU. Check if code 3774 is also present.

1. 1

   Sensor/Hose Replacement

   If the diagnostic checks reveal a faulty sensor (implausible readings) or damaged hoses, replace the differential pressure sensor and/or the hoses. Clear the fault codes and test run the machine.

2. 2

   Forced Regeneration

   If the sensor is functioning correctly and the restriction is due to soot buildup, park the tractor in a safe, well-ventilated area away from combustible materials. Use the CNH EST diagnostic tool to command a forced stationary (parked) DPF regeneration to burn off the accumulated soot.

3. 3

   DPF Removal and Cleaning

   If the forced regeneration fails, or if the diagnostic tool indicates the DPF is full of incombustible ash, the DPF must be removed from the exhaust system. Send the DPF to a certified facility for professional pneumatic/thermal ash cleaning, or replace the DPF assembly entirely.

4. 4

   ECU Reset

   If the DPF is cleaned or replaced, you must use the diagnostic tool to reset the DPF ash/soot accumulators in the Engine ECU. If this step is skipped, the ECU will still assume the filter is clogged and the code will return.