Case IH 3791 – Engine Control Unit (ECU) / Electronic Diesel Control (EDC): Diesel Particulate Filter (DPF): Diagnostic fault check for SRC high in Flow Resistance.

The system has detected that the flow resistance of the stored soot mass across the Diesel Particulate Filter is higher than the maximum allowed threshold. This indicates that the DPF is severely clogged with soot/ash, or that the differential pressure sensor is providing an erroneously high reading.

• Farmall
• Farmall 75C
• Farmall 85C
• Farmall 95C
• Farmall 105C
• Farmall 115C
• Farmall 115A
• Maxxum
• Puma
• Steiger
• SR175
• Combines

1. 1

   Inspect the DPF Differential Pressure Sensor and its electrical wiring harness for damage, corrosion, or shorts that could cause an out-of-range high voltage reading

2. 2

   Check the sensor hose lines connecting the DPF to the differential pressure sensor for blockages (soot buildup), melting, cracks, or detachment

3. 3

   Review soot mass and regeneration history using an electronic service tool (EST) to verify if regeneration is locked out due to excessive failed attempts

4. 4

   Check for physical exhaust restrictions or crushed pipes upstream or downstream of the DPF

1. 1

   Clear Minor Faults

   If the tractor allows, attempt to clear the code using the operator display panel or diagnostic tool to see if it is a hard, active fault.

2. 2

   Perform a Forced Regeneration

   If the soot load is high but the ECU has not completely locked out the system, initiate a manual/forced parked regeneration using the tractor's display or a diagnostic service tool. Ensure the machine is parked safely outdoors, away from combustible materials.

3. 3

   Clean or Replace Sensor/Hoses

   If the regeneration fails or the code immediately returns without the engine running, remove the DPF differential pressure sensor and blow out the hoses with compressed air. Replace the hoses if they are damaged. Replace the sensor if it fails electrical testing.

4. 4

   Remove and Service the DPF

   If the sensor and hoses are functioning correctly, the DPF itself is face-plugged or overloaded with ash. Remove the hood, air intake components, and heat shields. Disconnect the exhaust lines and temperature sensors. Unbolt and remove the DPF assembly. Send the DPF to a certified facility for professional ash cleaning, or install a new/remanufactured DPF.

5. 5

   Reset the ECU

   After replacing or cleaning the DPF, you must use a diagnostic tool to reset the DPF soot mass accumulator in the ECU so the system knows a clean filter has been installed.