Case IH 3790 – Engine Control Unit (ECU): Diesel particulate filter (DPF) : Signal range check flow resistance of the particulate filter - max.

This code indicates that the flow resistance across the Diesel Particulate Filter (measured as a pressure drop from the inlet to the outlet) has reached its maximum allowable limit. This typically means the DPF is severely restricted or completely overloaded with soot/ash, or there is a malfunction in the differential pressure sensor reading the flow resistance.

• Farmall
• SR250
• SV300
• Farmall 105C
• Farmall 115C
• Farmall 80V
• Quantum V/F series
• Puma

1. 1

   Inspect the hoses connecting the DPF to the differential pressure sensor for detached, melted, or blocked lines (a blocked hose can cause an implausible pressure drop reading).

2. 2

   Verify the differential pressure sensor circuit isn't shorted or open, and check for related electrical fault codes (such as 3797 or 3798).

3. 3

   Use the Case IH Electronic Service Tool (EST) to check the calculated soot and ash accumulation levels.

4. 4

   Check regeneration history to see if automatic regeneration has been taking too long or failing, which indicates the filter is packed with incombustible ash.

1. 1

   Clear Blockages

   If the differential pressure sensor hoses are clogged with soot or damaged, clear the lines or replace the hoses.

2. 2

   Sensor Replacement

   If the hoses are clear but the sensor is outputting a maxed-out voltage reading at rest, replace the DPF differential pressure sensor.

3. 3

   DPF Servicing

   If the sensor and lines are functioning correctly, the DPF is physically overloaded. Remove the DPF from the exhaust assembly and have the DPF professionally cleaned (ash removal service) or replace the DPF unit entirely.

4. 4

   Reset Parameters

   Crucial Step — After cleaning or replacing the DPF, you must connect the Case IH service tool and reset the DPF parameters (ash load reset / self-learning parameters). If this is not done, the ECU will still assume the filter is clogged and the code will remain active.

5. 5

   Retest

   Run the engine and perform a manual/service regeneration to ensure the flow resistance returns to normal operating parameters.